Unify UNSPEC_MASKED_EQ/GT to the form of UNSPEC_PCMP.

Unify UNSPEC_MASKED_EQ/GT to the form of UNSPEC_PCMP.

Currently for evex vpcmpeqb instruction, we have two forms of rtl
template representation, one is (unspec [op1 op2] UNSPEC_MASK_EQ), the
other is (unspec [op1, op2, const_int 0] UNSPEC_PCMP), which increases
the maintenance burden, such as optimization (not: vpcmpeqb)
to (vpcmpneqb) requires two define_insn_and_split to match the two
forms respectively, this patch removes UNSPEC_MASK_EQ/GT, unifying
them into the form of UNSPEC_PCMP.

gcc/ChangeLog:

	* config/i386/sse.md (*<avx512>_ucmp<mode>3_1): Change from
	define_split to define_insn_and_split.
	(*avx2_eq<mode>3): Removed.
	(<avx512>_eq<mode>3<mask_scalar_merge_name>): Adjust pattern
	(<avx512>_eq<mode>3<mask_scalar_merge_name>_1): Rename to ..
	(*<avx512>_eq<mode>3<mask_scalar_merge_name>_1): .. this, and
	adjust pattern.
	(*avx2_gt<mode>3): Removed.
	(<avx512>_gt<mode>3<mask_scalar_merge_name>): Change from
	define_insn to define_expand, and adjust pattern.
	(UNSPEC_MASKED_EQ, UNSPEC_MASKED_GT): Removed.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/avx512bw-vpcmpeqb-1.c: Adjust testcase.
	* gcc.target/i386/avx512bw-vpcmpeqw-1.c: Ditto.
	* gcc.target/i386/avx512bw-vpcmpgtb-1.c: Ditto.
	* gcc.target/i386/avx512bw-vpcmpgtw-1.c: Ditto.
	* gcc.target/i386/avx512f-vpcmpeqd-1.c: Ditto.
	* gcc.target/i386/avx512f-vpcmpeqq-1.c: Ditto.
	* gcc.target/i386/avx512f-vpcmpgtd-1.c: Ditto.
	* gcc.target/i386/avx512f-vpcmpgtq-1.c: Ditto.
	* gcc.target/i386/avx512vl-vpcmpeqd-1.c: Ditto.
	* gcc.target/i386/avx512vl-vpcmpeqq-1.c: Ditto.
	* gcc.target/i386/avx512vl-vpcmpgtd-1.c: Ditto.
	* gcc.target/i386/avx512vl-vpcmpgtq-1.c: Ditto.
	* gcc.target/i386/bitwise_mask_op-1.c: Ditto.
	* gcc.target/i386/bitwise_mask_op-2.c: Ditto.