[APX CCMP] Support ccmp for float compare

[APX CCMP] Support ccmp for float compare

The ccmp insn itself doesn't support fp compare, but x86 has fp comi
insn that changes EFLAG which can be the scc input to ccmp. Allow
scalar fp compare in ix86_gen_ccmp_first except ORDERED/UNORDERD
compare which can not be identified in ccmp.

gcc/ChangeLog:

	* config/i386/i386-expand.cc (ix86_gen_ccmp_first):
	Add fp compare and check the allowed fp compare type.
	(ix86_gen_ccmp_next): Adjust compare_code input to ccmp for
	fp compare.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/apx-ccmp-1.c: Add test for fp compare.
	* gcc.target/i386/apx-ccmp-2.c: Likewise.