mips: add MSA vec_cmp and vec_cmpu expand pattern [PR101132]

mips: add MSA vec_cmp and vec_cmpu expand pattern [PR101132]

Middle-end started to emit vec_cmp and vec_cmpu since GCC 11, causing
ICE on MIPS with MSA enabled.  Add the pattern to prevent it.

gcc/

	PR target/101132
	* config/mips/mips-protos.h (mips_expand_vec_cmp_expr): Declare.
	* config/mips/mips.c (mips_expand_vec_cmp_expr): New function.
	* config/mips/mips-msa.md (vec_cmp<MSA:mode><mode_i>): New
	  expander.
	  (vec_cmpu<IMSA:mode><mode_i>): New expander.

gcc/testsuite/

	PR target/101132
	* gcc.target/mips/pr101132.c: New test.