Don't fold __builtin_ia32_blendvpd w/o sse4.2.
__builtin_ia32_blendvpd is defined under sse4.1 and gimple folded
to ((v2di) c) < 0 ? b : a where vec_cmpv2di is under sse4.2 w/o which
it's veclowered to scalar operations and not combined back in rtl.
gcc/ChangeLog:
PR target/104946
* config/i386/i386-builtin.def (BDESC): Add
CODE_FOR_sse4_1_blendvpd for IX86_BUILTIN_BLENDVPD.
* config/i386/i386.cc (ix86_gimple_fold_builtin): Don't fold
__builtin_ia32_blendvpd w/o sse4.2
gcc/testsuite/ChangeLog:
* gcc.target/i386/sse4_1-blendvpd-1.c: New test.