We already had a check in configure of the actual build. This patch
adds it to the configure of the bindists too.

We weren't forcing enough recompilationg when package dependencies
changed, with the result that bumping a package version could lead to
linking failures or other problems later.

The problem/solutation are described on the wiki:

http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/RecompilationAvoidance#Packageversionchanges

currently deepseq, parallel, stm.

Allow a temporary assignment to be pushed past an assignment to a
global if the global is not mentioned in the rhs of the assignment we
are inlining.

This fixes up some bad code.  We should make sure we're doing
something equivalent in the new backend in due course.

Should fix an occasional build error of the form 
 ghc-pkg: too few bytes. Failed reading at byte position 8

The symptom is that under some rare conditions when running in
parallel, an unsafePerformIO or unsafeInterleaveIO computation might
be duplicated, so e.g. lazy I/O might give the wrong answer (the
stream might appear to have duplicate parts or parts missing).

I have a program that demonstrates it -N3 or more, some lazy I/O, and
a lot of shared mutable state.  See the comment with stg_noDuplicatezh
in PrimOps.cmm that explains the problem and the fix.  This took me
about a day to find :-(

Following recent changes to the numbering of registers, we overflowed
Word32 on x86-64, with the result that xmm8 and later we not being
allocated.

To print HsTypes correctly we should remember whether the Kind on
a HsTyVarBndr came from type inference, or was put there by the
user.  See Note [Printing KindedTyVars] in HsTypes.  So instead of
changing a UserTyVar to a KindedTyVar during kind checking, we
simply add a PostTcKind to the UserTyVar.

The change was provoked by Trac #3830, although other changes
mean that #3830 gets a diferent and better error message now.
So this patch is simply doing the Right Thing for the future.

This patch also fixes Trac #3845, which was caused by a *type splice*
not remembering the free *term variables* mentioned in it.  Result
was that we build a 'let' when it should have been 'letrec'.
Hence a new FreeVars field in HsSpliceTy.

While I was at it, I got rid of HsSpliceTyOut and use a PostTcKind
on HsSpliceTy instead, just like on the UserTyVar.

The simplifier is taking more iterations than it should, because we
were fruitlessly ANF-ing a top-level declaration of form

   x = Ptr "foo"#

to get
 
   x = let v = "foo"# in Ptr v

and then inlining v again.  This patch makes Simplify.makeTrivial 
top-level aware, so that it doesn't ANF if it's going to be undone.

After some discussion we decided to make a quasi-quote look like

   [pads| ...blah... |]

rather than

   [$pads| ...blah... |]

as before. The new syntax is quieter, although it does not signal
quite as clearly that there is a splice going on.

a) Added quasi-quote forms for
      declarations
      types
   e.g.   f :: [$qq| ... |]

b) Allow Template Haskell pattern quotes (but not splices)
   e.g.  f x = [p| Int -> $x |]

c) Improve pretty-printing for HsPat to remove superfluous
   parens.  (This isn't TH related really, but it affects
   some of the same code.)


A consequence of (a) is that when gathering and grouping declarations
in RnSource.findSplice, we must expand quasiquotes as we do so.
Otherwise it's all fairly straightforward.  I did a little bit of
refactoring in TcSplice.

User-manual changes still to come.

At least until we switch to --lazy being the default

This patch simply avoids a needless difference in behaviour from 
6.10, and one that happens to affect HList. See Note [Stupid theta].