x86: Remove OPTION_MASK_ISA_SSE4_2 from CRC32 _builtin functions

x86: Remove OPTION_MASK_ISA_SSE4_2 from CRC32 _builtin functions

Since

commit 39671f87b2df6a1894cc11a161e4a7949d1ddccd
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Apr 15 05:59:48 2021 -0700

    x86: Use crc32 target option for CRC32 intrinsics

enabled OPTION_MASK_ISA_CRC32 for -msse4 and removed TARGET_SSE4_2 check
in sse4_2_crc32<mode> pattens, remove OPTION_MASK_ISA_SSE4_2 from CRC32
_builtin functions.

gcc/

	PR target/101549
	* config/i386/i386-builtin.def: Remove OPTION_MASK_ISA_SSE4_2
	from CRC32 _builtin functions.

gcc/testsuite/

	PR target/101549
	* gcc.target/i386/crc32-6.c: New test.