Add folding and remove expanders for x86 *pcmp{et,gt}* builtins [PR target/98911]

Add folding and remove expanders for x86 *pcmp{et,gt}* builtins [PR target/98911]

gcc/ChangeLog:

	PR target/98911
	* config/i386/i386-builtin.def (BDESC): Change the icode of
	the following builtins to CODE_FOR_nothing.
	* config/i386/i386.c (ix86_gimple_fold_builtin): Fold
	IX86_BUILTIN_PCMPEQB128, IX86_BUILTIN_PCMPEQW128,
	IX86_BUILTIN_PCMPEQD128, IX86_BUILTIN_PCMPEQQ,
	IX86_BUILTIN_PCMPEQB256, IX86_BUILTIN_PCMPEQW256,
	IX86_BUILTIN_PCMPEQD256, IX86_BUILTIN_PCMPEQQ256,
	IX86_BUILTIN_PCMPGTB128, IX86_BUILTIN_PCMPGTW128,
	IX86_BUILTIN_PCMPGTD128, IX86_BUILTIN_PCMPGTQ,
	IX86_BUILTIN_PCMPGTB256, IX86_BUILTIN_PCMPGTW256,
	IX86_BUILTIN_PCMPGTD256, IX86_BUILTIN_PCMPGTQ256.
	* config/i386/sse.md (avx2_eq<mode>3): Deleted.
	(sse2_eq<mode>3): Ditto.
	(sse4_1_eqv2di3): Ditto.
	(sse2_gt<mode>3): Rename to ..
	(*sse2_gt<mode>3): .. this.

gcc/testsuite/ChangeLog:

	PR target/98911
	* gcc.target/i386/pr98911.c: New test.
	* gcc.target/i386/funcspec-8.c: Replace __builtin_ia32_pcmpgtq
	with __builtin_ia32_pcmpistrm128 since it has been folded.