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Clean up code&interfaces that deals with timers and asynchrony:

- Timer.{c,h} now defines the platform-independent interface
  to the timing services needed by the RTS. Itimer.{c,h} +
  win32/Ticker.{c,h} defines the OS-specific services that
  creates/destroys a timer.
- For win32 plats, drop the long-standing use of the 'multimedia'
  API timers and implement the ticking service ourselves. Simpler
  and more flexible.
- Select.c is now solely for platforms that use select() to handle
  non-blocking I/O & thread delays. win32/AwaitEvent.c provides
  the same API on the Win32 side.
- support threadDelay on win32 platforms via worker threads.

Not yet compiled up on non-win32 platforms; will do once checked in.

Typos

Fix buglets in new unused-binding story

Use old-style foreign import for bkwd compatibility

-------------------------------------
	Improve the "unused binding" warnings
	-------------------------------------

We've had a succession of hacks for reporting warnings for
unused bindings.  Consider

	module M( f ) where

 	f x = x

	g x = g x + h x
	h x = x

Here, g mentions itself and h, but is not itself mentioned. So
really both g and h are dead code.  We've been getting this wrong
for ages, and every hack so far has failed on some simple programs.

This commit does a much better job.  The renamer applied to a bunch
of bindings returns a NameSet.DefUses, which is a dependency-ordered
lists of def/use pairs.  It's documented in NameSet.
Given this, we can work out precisely what is not used, in a nice
tidy way.

It's less convenient in the case of type and class declarations, because
the strongly-connected-component analysis can span module boundaries.
So things are pretty much as they were for these.


As usual, there was a lot of chuffing around tidying things up.
I havn't tested it at all thoroughly yet.

Various unrelated import-decl-pruning has been done too.

Import pruning

Import pruning, use mingw32_TARGET not HOST, use old-style foreign import (for 4.08 compat)

Import pruning

More tidy up

Small fix to a TH bug; this one concerning the constraint-gathering mechanism

Another typo; sigh

Typo

Debugging hook jiggling

Fix a type-error in desugaring TH code

Asynchronous / non-blocking I/O for Win32 platforms.

This commit introduces a Concurrent Haskell friendly view of I/O on
Win32 platforms. Through the use of a pool of worker Win32 threads, CH
threads may issue asynchronous I/O requests without blocking the
progress of other CH threads. The issuing CH thread is blocked until
the request has been serviced though.

GHC.Conc exports the primops that take care of issuing the
asynchronous I/O requests, which the IO implementation now takes
advantage of. By default, all Handles are non-blocking/asynchronous,
but should performance become an issue, having a per-Handle flag for
turning off non-blocking could easily be imagined&introduced.

[Incidentally, this thread pool-based implementation could easily be
extended to also allow Haskell code to delegate the execution of
arbitrary pieces of (potentially blocking) external code to another OS
thread. Given how relatively gnarly the locking story has turned out
to be with the 'threaded' RTS, that may not be such a bad idea.]

deja vu all over again

* Nuked unused --with-glut-api and --with-glut-xlib arguments
* Only check for OpenGL headers and libs when --enable-hopengl is given

typo

-------------------------------------
      Add Core Notes and the {-# CORE #-} pragma
	-------------------------------------

This is an idea of Hal Daume's. The key point is that Notes in Core
are augmented thus:

  data Note
    = SCC CostCentre
    | ...
    | CoreNote String     -- NEW

These notes can be injected via a Haskell-source pragma:

   f x = ({-# CORE "foo" #-} show) ({-# CORE "bar" #-} x)

This wraps a (Note (CoreNote "foo")) around the 'show' variable,
and a similar note around the argument to 'show'.

These notes are basically ignored by GHC, but are emitted into
External Core, where they may convey useful information.

Exactly how code involving these notes is munged by the simplifier
isn't very well defined.  We'll see how it pans out.  Meanwhile
the impact on the rest of the compiler is minimal.

Document {-# CORE #-} pragma (thanks to Hal Daume)

Import pruning

Add comments

Comments and imports only

closureSatisfiesConstraints: check whether the retainer set is valid
before attempting to match it against a constraint.  It might not be
valid if the object is an ex-weak-pointer which was finalized after
the last GC.

MERGE TO STABLE

-------------------------------------
	   Complete an earlier TH commit
	-------------------------------------

In this earlier commit:

  3.  Ensure that a declaration quotation [d| ... |] does not have a
      permanent effect on the instance environment. (A TH fix.)

I had forgotten to do a stage2 compile.  This commit just completes
the earlier work.  I moved some code from TcExpr (long) to TcSplice
(shorter) which had the happy effect of bringing related code together.

-------------------------------------
   Generate correct dependencies when reading External Core
	-------------------------------------

We have to be more careful than I realised when doing strongly-connected
component analysis of type/class decls when reading External Core.

Here's the relevant new comment:

--		Building edges for SCC analysis
--
-- When building the edges, we treat the 'main name' of the declaration as the
-- key for the node, but when dealing with External Core we may come across
-- references to one of the implicit names for the declaration.  For example:
--	class Eq a where ....
--	data :TSig a = :TSig (:TEq a) ....
-- The first decl is sucked in from an interface file; the second
-- is in an External Core file, generated from a class decl for Sig.
-- We have to recognise that the reference to :TEq represents a
-- dependency on the class Eq declaration, else the SCC stuff won't work right.
--
-- This complication can only happen when consuming an External Core file
--
-- Solution: keep an "EdgeMap" (bad name) that maps :TEq -> Eq.
-- Don't worry about data constructors, because we're only building
-- SCCs for type and class declarations here.  So the tiresome mapping
-- is need only to map   [class tycon -> class]

Part 2 of fix :i in InteractiveUI

Comments only

Another datacon-naming wibble

Fix :i in InteractiveUI

Eliminate brain-dead outputC pattern-match failure

Eliminate bogus string-literal duplication

Compile binary stuff with -O always

Add -fvia-C to utils/Panic_HC_OPTS, and remove it from main/Main_HC_OPTS.

odir-ify prelude/PrimOp.o dependency

Document phase control

-------------------------------------
	 	Two minor wibbles
	-------------------------------------


1.  Make the generic toT/fromT Ids for "generic derived classes" into
    proper ImplicitIds, with their own GlobalIdDetails. This makes it
    easier to identify them.  (The lack of this showed up as a bug
    when I made an apparently-innocuous other change.)

2.  Distinguish ClassOpIds from RecordSelIds in their GlobalIdDetails.
    They are treated differently here and there, so I made this change
    as part of (1)

3.  Ensure that a declaration quotation [d| ... |] does not have a
    permanent effect on the instance environment. (A TH fix.)

Wibbles to the new datacon story; fixes ds002

Add note to description of -no-hs-main: it forces linking in --make
mode too.

If -no-hs-main is specified in --make mode, attempt linking even when
there's no Main module.

Fixes bug #686620

MERGE TO STABLE