i386: Fix expand_vector_set for VEC_MERGE/VEC_DUPLICATE RTX [PR117116]

Middle end can generate SYMBOL_REF RTX as a value "val" in the call
to expand_vector_set, but SYMBOL_REF RTX is not accepted in
<sse2p4_1>_pinsr<ssemodesuffix> insn pattern, generated via
VEC_MERGE/VEC_DUPLICATE RTX path.

Force the value into a register before VEC_MERGE/VEC_DUPLICATE RTX
is generated if it doesn't satisfy nonimmediate_operand predicate.

	PR target/117116

gcc/ChangeLog:

	* config/i386/i386-expand.cc (expand_vector_set): Force "val"
	into a register before VEC_MERGE/VEC_DUPLICATE RTX is generated
	if it doesn't satisfy nonimmediate_operand predicate.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr117116.c: New test.