[rs6000] Fix x86-compat vector intrinsics testcases for BE, 32bit

[rs6000] Fix x86-compat vector intrinsics testcases for BE, 32bit

Fix general endian issues found in the test cases for thecompatibility
implementations of the x86 vector intrinsics.  (The tests had been
inadvertently made to PASS without actually running the test code.
A later patch fixes this issue.)

Additionally, a new <smmintrin.h> is added, as some of the APIs therein are
now used by the test cases.  It is _not_ a complete implementation of the
SSE4 interfaces, only the few "extract" interfaces uses by the tests.

2018-12-06  Paul A. Clarke  <pc@us.ibm.com>

[gcc]

	PR target/88316
	* config/rs6000/smmintrin.h: New file.
	* config.gcc: Add smmintrin.h to extra_headers for powerpc*-*-*.

[gcc/testsuite]

	PR target/88316
	* gcc.target/powerpc/mmx-packssdw-1.c: Fixes for big-endian.
	* gcc.target/powerpc/mmx-packsswb-1.c: Likewise.
	* gcc.target/powerpc/mmx-packuswb-1.c: Likewise.
	* gcc.target/powerpc/mmx-pmulhw-1.c: Likewise.
	* gcc.target/powerpc/sse-cvtpi32x2ps-1.c: Likewise.
	* gcc.target/powerpc/sse-cvtpu16ps-1.c: Likewise.
	* gcc.target/powerpc/sse-cvtss2si-1.c: Likewise.
	* gcc.target/powerpc/sse-cvtss2si-2.c: Likewise.
	* gcc.target/powerpc/sse2-pshufhw-1.c: Likewise.
	* gcc.target/powerpc/sse2-pshuflw-1.c: Likewise.

From-SVN: r266869