PR target/53283
	* config/i386/i386.c (ix86_fold_builtin): Call SUBTARGET_FOLD_BUILTIN
	if defined.
	* config/darwin.h: Rename TARGET_FOLD_BUILTIN to
	SUBTARGET_FOLD_BUILTIN.
	* config/rs6000/darwin.h: Map TARGET_FOLD_BUILTIN onto
	SUBTARGET_FOLD_BUILTIN.

From-SVN: r189391