Optimize vpsubusw compared to 0 into vpcmpleuw or vpcmpnleuw [PR96906]

Optimize vpsubusw compared to 0 into vpcmpleuw or vpcmpnleuw [PR96906]

For signed comparisons, it handles cases that are eq or neq to 0.
For unsigned comparisons, it additionaly handles cases that are le or
gt to 0(equivilent to eq or neq to 0). Transform case eq to leu,
case neq to gtu.

.i.e. for -mavx512bw -mavx512vl transform eq case code from

	vpsubusw        %xmm1, %xmm0, %xmm0
	vpxor   %xmm1, %xmm1, %xmm1
	vpcmpeqw  %xmm1, %xmm0, %k0
to
	vpcmpleuw       %xmm1, %xmm0, %k0

.i.e. for -mavx512bw -mavx512vl transform neq case code from

	vpsubusw        %xmm1, %xmm0, %xmm0
	vpxor   %xmm1, %xmm1, %xmm1
	vpcmpneqw  %xmm1, %xmm0, %k0
to
	vpcmpnleuw       %xmm1, %xmm0, %k0

gcc/ChangeLog
	PR target/96906
	* config/i386/sse.md
	(<avx512>_ucmp<mode>3<mask_scalar_merge_name>): Add a new
	define_split after this insn.

gcc/testsuite/ChangeLog

	* gcc.target/i386/avx512bw-pr96906-1.c: New test.
	* gcc.target/i386/pr96906-1.c: Add -mno-avx512f.