[SPARC] Add -mfsmuld option

[SPARC] Add -mfsmuld option

Add the -mfsmuld option to control the generation of the FsMULd
instruction.  In general, this instruction is available in architecture
version V8 and V9 CPUs with FPU.  Some CPUs of this category do not
support this instruction properly, e.g. AT697E, AT697F and UT699.  Some
CPUs of this category do not implement it in hardware, e.g. LEON3/4 with
GRFPU-lite.

gcc/
	* config/sparc/sparc.c (dump_target_flag_bits): Dump MASK_FSMULD.
	(sparc_option_override): Honour MASK_FSMULD.
	* config/sparc/sparc.h (MASK_FEATURES): Add MASK_FSMULD.
	* config/sparc/sparc.md (muldf3_extend): Use TARGET_FSMULD.
	* config/sparc/sparc.opt (mfsmuld): New option.
	* doc/invoke.texi (mfsmuld): Document option.

From-SVN: r250570