Fix the SSSE3 CPUID detection.

SSSE3 is detected by bit 9 of ECX, but we were checking bit 9 of EDX
which is APIC leading to SSSE3 routines being called on CPUs without
SSSE3.

Reviewed-by: Matt Turner <mattst88@gmail.com>
test/utils.c: Make the stack unaligned only on 32 bit Windows

The call_test_function() contains some assembly that deliberately
causes the stack to be aligned to 32 bits rather than 128 bits on
x86-32. The intention is to catch bugs that surface when pixman is
called from code that only uses a 32 bit alignment.

However, recent versions of GCC apparently make the assumption (either
accidentally or deliberately) that that the incoming stack is aligned
to 128 bits, where older versions only seemed to make this assumption
when compiling with -msse2. This causes the vector code in the PRNG to
now segfault when called from call_test_function() on x86-32.

This patch fixes that by only making the stack unaligned on 32 bit
Windows, where it would definitely be incorrect for GCC to assume that
the incoming stack is aligned to 128 bits.

V2: Put "defined(...)" around __GNUC__

Reviewed-and-Tested-by: Matt Turner <mattst88@gmail.com>
Bugzilla: https://bugs.gentoo.org/show_bug.cgi?id=491110
Merge branch 'master' of git://anongit.freedesktop.org/git/pixman