i386: Rewrite check for AVX512 features

i386: Rewrite check for AVX512 features

Add a new file, avx512-check.h, to check all AVX512 features.  The test
is skipped if any requested AVX512 features are unavailable.

	PR target/81590
	* gcc.target/i386/avx512-check.h: New file.
	* gcc.target/i386/avx5124fmaps-check.h: Removed.
	* gcc.target/i386/avx5124vnniw-check.h: Likewise.
	* gcc.target/i386/avx512cd-check.h: Likewise.
	* gcc.target/i386/avx512ifma-check.h: Likewise.
	* gcc.target/i386/avx512vbmi-check.h: Likewise.
	* gcc.target/i386/avx512vpopcntdq-check.h: Likewise.
	* gcc.target/i386/avx512bw-check.h: Rewrite.
	* gcc.target/i386/avx512dq-check.h: Likewise.
	* gcc.target/i386/avx512er-check.h: Likewise.
	* gcc.target/i386/avx512f-check.h: Likewise.
	* gcc.target/i386/avx512vl-check.h: Likewise.
	* gcc.target/i386/avx512f-helper.h: Include "avx512-check.h"
	only.
	(test_512): Removed.
	(avx512*_test): Likewise.
	* gcc.target/i386/avx512f-pr71559.c (TEST): Undef.

From-SVN: r250875