Add support for floating-point fused multiply-add on Sparc.

Add support for floating-point fused multiply-add on Sparc.

	* configure.ac: Add feature check to make sure the assembler
	supports the FMAF, HPC, and VIS 3.0 instructions found on
	Niagara-3 and later cpus.
	* configure: Rebuild.
	* config.in: Likewise.
	* config/sparc/sparc.opt: New option '-mfmaf'.
	* config/sparc/sparc.md: Add float fused multiply-add patterns.
	* config/sparc/sparc.h (AS_NIAGARA3_FLAG): New macro.
	(ASM_CPU64_DEFAULT_SPEC, ASM_CPU_SPEC): Use it, as needed.
	* config/sparc/sol2.h (ASM_CPU32_DEFAULT_SPEC,
	ASM_CPU64_DEFAULT_SPEC, ASM_CPU_SPEC): Likewise.
	* config/sparc/sparc.c (sparc_option_override): Turn MASK_FMAF on
	by default for Niagara-3 and later.  Turn it off if TARGET_FPU is
	disabled.
	(sparc_rtx_costs): Handle 'FMA'.
	* doc/invoke.texi: Document -mfmaf.

From-SVN: r179174