Add combine splitter to transform vashr/vlshr/vashl_optab to...

Add combine splitter to transform vashr/vlshr/vashl_optab to ashr/lshr/ashl_optab for const vector duplicate operand.

gcc/ChangeLog:

	PR target/101796
	* config/i386/predicates.md (const_vector_operand):
	Add new predicate.
	* config/i386/sse.md(<insn><mode>3<mask_name>):
	Add new define_split below.

gcc/testsuite/ChangeLog:

	PR target/101796
	* gcc.target/i386/pr101796-1.c: New test.