i386: Fix up expander conditions on cbranchbf4 and cstorebf4 [PR107969]

i386: Fix up expander conditions on cbranchbf4 and cstorebf4 [PR107969]

With -msoft-float we ICE on __bf16 comparisons, because the
insns we want to use under the hood (cbranchsf4 and cstoresf4)
after performing the fast extensions aren't available.

The following patch copies the conditions from the c*sf4 expanders
to the corresponding c*bf4 expanders.

2022-12-06  Jakub Jelinek  <jakub@redhat.com>

	PR target/107969
	* config/i386/i386.md (cbranchbf4, cstorebf4): Guard expanders
	with the same condition as cbranchsf4 or cstoresf4 expanders.

	* gcc.target/i386/pr107969.c: New test.