Fixes validate on amd64/Linux with:

SRC_CC_OPTS += -Wmissing-parameter-type
SRC_CC_OPTS += -Wold-style-declaration
SRC_CC_OPTS += -Wold-style-definition

functions need to be given a new name, and the header files contain
some __asm hackery in order to let the program call the correct function.

This mean that you need to use the header files in order to call the
correct system functions, which prevents things like "foreign import ccall" from working.

Ghc solves this with wrapper functions for some of the renamed functions,
but it has not been updated for newer versions of NetBSD that has recently
versioned some more functions.

The attached patches introduces wrapper functions for all currently
NetBSD-versioned functions used in libraries/unix.  Solves ~20 testsuite
failures.

Contributed by: Krister Walfridsson <krister.walfridsson@gmail.com>

leaving out Windows-specific hacks

If they are included into a C file which also has certain symbols
defined, then the behaviour of the HsUnix.h functions can change
(e.g. lstat can become the 32bit, rather than 64bit, version).

Since we switched to using timer_create() in the RTS, this function
has been failing to disables the timer interrupts.  This turns out to
be the cause of the random framework failures in the test suite.
Invoking the RTS to turn off the timer signal is the right thing.

Also adds System.Posix.Process.Internals in order to make the deps work out.

Process reorganisation: the System.Process library moves into base,
and System.Cmd is re-implemented in terms of it.

Thanks to Krasimir Angelov, we have a version of System.Process that
doesn't rely on the unix or Win32 libraries.  Normally using
unix/Win32 would be the right thing, but since we want to implement
System.Cmd on top of this, and GHC uses System.Cmd, we can't introduce
a bunch of .hsc dependencies into GHC's bootstrap libraries.

So, the new version is larger, but has fewer dependencies.  I imagine
it shouldn't be too hard to port to other compilers.

Warning police #14: Help gcc a bit with variables which are not
obviously always used.

More POSIX bits... we're getting there.