rs6000: Remove vcond{,u} expanders

rs6000: Remove vcond{,u} expanders

As PR114189 shows, middle-end will obsolete vcond, vcondu
and vcondeq optabs soon.  This patch is to remove all
vcond{,u} expanders in rs6000 port and adjust the function
rs6000_emit_vector_cond_expr which is called by those
expanders as static.

	PR target/115659

gcc/ChangeLog:

	* config/rs6000/rs6000-protos.h (rs6000_emit_vector_cond_expr): Remove.
	* config/rs6000/rs6000.cc (rs6000_emit_vector_cond_expr): Add static
	qualifier as it is only called by rs6000_emit_swsqrt now.
	* config/rs6000/vector.md (vcond<VEC_F:mode><VEC_F:mode>): Remove.
	(vcond<VEC_I:mode><VEC_I:mode>): Remove.
	(vcondv4sfv4si): Likewise.
	(vcondv4siv4sf): Likewise.
	(vcondv2dfv2di): Likewise.
	(vcondv2div2df): Likewise.
	(vcondu<VEC_I:mode><VEC_I:mode>): Likewise.
	(vconduv4sfv4si): Likewise.
	(vconduv2dfv2di): Likewise.