Remove THREAD_STATS.

A THREAD_STATS macro duplicates gathering information that could be
obtained by systemtap probes instead.
Deduplicate setenv.

Setenv contained a code path that was redundant as it could be handled
in general case.
Fix previous commit.
Use glibc_likely instead __builtin_expect.
Move tilegx, tilepro, and linux-generic from ports to libc.

I've moved the TILE-Gx and TILEPro ports to the main sysdeps hierarchy,
along with the linux-generic ports infrastructure.  Beyond the README
update, the move was just

    git mv ports/sysdeps/tile sysdeps/tile
    git mv ports/sysdeps/unix/sysv/linux/tile \
      sysdeps/unix/sysv/linux/tile
    git mv ports/sysdeps/unix/sysv/linux/generic \
      sysdeps/unix/sysv/linux/generic

I updated the relevant ChangeLogs along the lines of the ARM move
in commit c6bfe5c4d75 and tested the 64-bit tilegx build to confirm that
there were no changes in "objdump -dr" output in the shared objects.
Remove mips dependency on alpha.

This patch removes an unnecessary dependency of the mips port on alpha
by including a powerpc file directly where previously the mips file
included the alpha one which then included the powerpc one.

	* sysdeps/unix/sysv/linux/mips/ipc_priv.h: Directly include
	sysdeps/unix/sysv/linux/powerpc/ipc_priv.h instead of via
	sysdeps/unix/sysv/linux/alpha/ipc_priv.h.
Move m68k from ports to libc
Whitespace fixes
Move shared umount.c from hppa to mips.

This patch prepares for moving mips from ports to libc by reversing
the #include ordering between mips and hppa.

Reversing #include ordering for umount.c is the conservative change in
preparation for moving the mips port.  In fact, it appears there are
several redundant umount.c files all implementing umount in terms of
the umount2 syscall; I've filed bug 16552 for eliminating that
redundancy properly.

Tested that disassembly of shared libraries for mips (o32, n32, n64)
is the same before and after this patch.

	* sysdeps/unix/sysv/linux/hppa/umount.c: Move to
	sysdeps/unix/sysv/linux/mips/mips64/umount.c and #include that
	file.

	* sysdeps/unix/sysv/linux/mips/mips64/umount.c: Move from
	sysdeps/unix/sysv/linux/hppa/umount.c instead of #include of that
	file.
Move mips from ports to libc.

I've moved the MIPS port from ports to the main sysdeps hierarchy.
Beyond the README update, the move of the files was simply

git mv ports/sysdeps/mips sysdeps/mips
git mv ports/sysdeps/unix/mips sysdeps/unix/mips
git mv ports/sysdeps/unix/sysv/linux/mips sysdeps/unix/sysv/linux/mips

and in addition to the ChangeLog entries here, I put a note at the top
of ports/ChangeLog.mips similar to those in other files.

Tested that disassembly of installed shared libraries for mips is the
same before and after this patch (except for ld.so where paths in
assertions are involved, as for arm).

	* sysdeps/mips: Move directory from ports/sysdeps/mips.
	* sysdeps/unix/mips: Move directory from ports/sysdeps/unix/mips.
	* sysdeps/unix/sysv/linux/mips: Move directory from
	ports/sysdeps/unix/sysv/linux/mips.
	* README: Update listing for mips-*-linux-gnu and
	mips64-*-linux-gnu.

	* sysdeps/mips: Move directory to ../sysdeps/mips.
	* sysdeps/unix/mips: Move directory to ../sysdeps/unix/mips.
	* sysdeps/unix/sysv/linux/mips: Move directory to
	../sysdeps/unix/sysv/linux/mips.
Fix whitespace in MIPS files to allow move.