PR target/40017
	* config/rs6000/rs6000-c.c (_Bool_keyword): New variable.
	(altivec_categorize_keyword, init_vector_keywords,
	rs6000_cpu_cpp_builtins): Define _Bool as conditional macro
	similar to bool.

	* gcc.target/powerpc/altivec-types-1.c: Don't expect error for
	__vector _Bool.
	* gcc.target/powerpc/altivec-30.c: New test.
	* gcc.target/powerpc/altivec-31.c: New test.

From-SVN: r147970