MFC	r258081, r258138, r258143, r258179, r258157, r258204, 258205,
	r258206, r258207, r258321

This is a series of commits inspired on Google's gcc-4.2.1 for
Android that were taken from the gcc pre-4.3 under the GPLv2.

gcc: Backport fixes for -W parentheses in C++
	This fixes GCC 19564.
gcc: merge rs6000 change from FSF pre-gcc43
	Don't set MASK_PPC_GFXOPT for 8540 or 8548.
Merge vrp-tree fix from gcc-4.3
	Fix missed conversion from / to >> (GCC PR32521)
Merge in GCCr120505 to include definition of TREE_OVERFLOW_P
gcc: warn about integer overflow in constant expressions in the C++ frontend.
gcc: Add a new option -Wvla to warn variable length array.
libcpp: preprocessor speedup patches from upstream gcc.
gcc: add femit-struct-debug support to reduce Reduce dwarf debug size
gcc: Fix postreload-gcse treatment of call-clobbered registers.
gcc: Record some previous commits in the ChangeLog.gcc43 file.