[rs6000] Enable x86-compat vector intrinsics testing

[rs6000] Enable x86-compat vector intrinsics testing

The testsuite tests for the compatibility implementations of x86 vector
intrinsics for "powerpc" had been inadvertently made to PASS
without actually running the test code.

This patch removes the code which kept the tests from running the actual
test code.

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

[gcc/testsuite]

	PR target/88316
	* gcc.target/powerpc/bmi-check.h: Remove test for
	__BUILTIN_CPU_SUPPORTS__, thereby enabling test code to run.
	* gcc.target/powerpc/bmi2-check.h: Likewise.
	* gcc.target/powerpc/mmx-check.h: Likewise.
	* gcc.target/powerpc/sse-check.h: Likewise.
	* gcc.target/powerpc/sse2-check.h: Likewise.
	* gcc.target/powerpc/sse3-check.h: Likewise.

From-SVN: r266870