Fix up dg options to resolve make check failures Bill Seurer found

Fix up dg options to resolve make check failures Bill Seurer found
when compiling --with-cpu=power6.

2017-05-31  Steven Munroe  <munroesj@gcc.gnu.org>

	* gcc.target/powerpc/bmi2-pdep32-1.c: Add -mcpu=power7 to
        dg-options.  Change dg-require-effective-target powerpc_vsx_ok
        to vsx_hw.  Add dg-skip-if directive to disable this test if
	-mcpu overridden.
	* gcc.target/powerpc/bmi2-pdep64-1.c: Likewise.
	* gcc.target/powerpc/bmi2-pext32-1.c: Likewise.
	* gcc.target/powerpc/bmi2-pext64-1.c: Likewise.
	* gcc.target/powerpc/bmi2-pext64-1a.c: Add -mcpu=power7
	to dg-option.  Add dg-skip-if directive to disable this test
	for darwin.  Add dg-skip-if directive to disable this test if
	-mcpu overridden.

From-SVN: r248766