PowerPC: optimized strpbrk for POWER7

This patch add an optimized strpbrk for POWER7 by using a different
algorithm than default implementation: it constructs a table based on
the 'accept' argument and use this table to check for any occurance on
the input string. The idea is similar as x86_64 uses.
For PowerPC some tunings were added, such as unroll loops and memory
clear using VSX instructions.
Fix -Wundef warnins for __FP_FAST_FMA*

The macros are defined by the compiler, so we can only verify whether
they are defined or not.
Implement benchmarking script in python

Implemented the benchmark script in python since it is much cleaner
and simpler to maintain.
ChangeLog formatting fix
Fix log (1) in round-downward mode (bug 16731).

According to ISO C Annex F, log (1) should be +0 in all rounding
modes, but some implementations in glibc wrongly return -0 in
round-downward mode (mapping to log1p (x - 1) is problematic because 1
- 1 is -0 in round-downward mode, and log1p (-0) is -0).  This patch
fixes this.  (It helps with some implementations of other functions
such as acosh, log2 and log10 that call out to log, but not enough to
enable all-rounding-modes testing for those functions without further
fixes to other implementations of them.)

Tested x86_64 and x86 and ulps updated accordingly, and did spot tests
for mips64 for the ldbl-128 fix, and i586 for the sysdeps/i386/fpu
implementations shadowed by those in sysdeps/i386/i686/fpu.

	[BZ #16731]
	* sysdeps/i386/fpu/e_log.S (__ieee754_log): Take absolute value
	when x - 1 is zero.
	* sysdeps/i386/fpu/e_logf.S (__ieee754_logf): Likewise.
	* sysdeps/i386/fpu/e_logl.S (__ieee754_logl): Likewise.
	* sysdeps/i386/i686/fpu/e_logl.S (__ieee754_logl): Likewise.
	* sysdeps/ieee754/dbl-64/e_log.c (__ieee754_log): Return +0 when
	argument is 1.
	* sysdeps/ieee754/ldbl-128/e_logl.c (__ieee754_logl): Likewise.
	* sysdeps/x86_64/fpu/e_logl.S: Take absolute value when x - 1 is
	zero.
	* math/libm-test.inc (log_test): Use ALL_RM_TEST.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
Fix -Wundef warnings for _ABI* on MIPS.

This patch fixes -Wundef warnings related to the _ABI* macros on MIPS.
GCC predefines only the _ABI* macro related to the ABI actually in
use, meaning that a conditional such as "#if _MIPS_SIM == _ABI64" is
true only for the ABI in question (all the macros are nonzero), but
produces a -Wundef warning for the other ABIs.  The normal approach to
using these macros is to include <sgidefs.h>, which ensures that all
three _ABI* macros are defined rather than just one; this patch does
so in the places that caused warnings (the bulk of the warnings
arising from <bits/wordsize.h>).  Tested that the warnings are fixed.

	* sysdeps/mips/bits/wordsize.h: Include <sgidefs.h>.
	* sysdeps/unix/sysv/linux/mips/getrlimit64.c: Likewise.
	* sysdeps/unix/sysv/linux/mips/setrlimit64.c: Likewise.