Fix sparc when assembler lacks support for vis3/fmaf instructions.

gcc/

	* config/sparc/sparc.h: Do not force TARGET_VIS3 and TARGET_FMAF
	to zero when assembler lacks support for such instructions.
	* config/sparc/sparc.c (sparc_option_override): Clear MASK_VIS3
	and MASK_FMAF in defaults when assembler lacks necessary support.

gcc/testsuite/

	* gcc.target/sparc/cmask.c: Remove 'vis3' target check and specify
	'-mvis3' instead of 'mcpu=niagara3' in options.
	* gcc.target/sparc/fhalve.c: Likewise.
	* gcc.target/sparc/fnegop.c: Likewise.
	* gcc.target/sparc/fpadds.c: Likewise.
	* gcc.target/sparc/fshift.c: Likewise.
	* gcc.target/sparc/fucmp.c: Likewise.
	* gcc.target/sparc/lzd.c: Likewise.
	* gcc.target/sparc/vis3misc.c: Likewise.
	* gcc.target/sparc/xmul.c: Likewise.

From-SVN: r179875