re PR target/66824 (-miamcu doesn't load FP constant into register directly)

re PR target/66824 (-miamcu doesn't load FP constant into register directly)

	PR target/66824
	* config/i386/i386.h (TARGET_HARD_SF_REGS): New define.
	(TARGET_HARD_DF_REGS): Ditto.
	(TARGET_HARD_XF_REGS): Ditto.
	* config/i386/i386.md (*movxf_internal): Add alternatives 9 and 10.
	Enable alternatives 9 and 10 only for !TARGET_HARD_XF_REG target.
	(*movdf_internal): Add alternatives 22, 23, 24 and 25. Enable
	alternatives 22, 23, 24 and 25 only for !TARGET_HARD_DF_REG target.
	(*movsf_internal): Add alternatives 16 and 17. Enable
	alternatives 16 and 17 only for !TARGET_HARD_SF_REG target.

From-SVN: r225919