i386: Don't use AVX512F integral masks for V*TImode [PR94438]

i386: Don't use AVX512F integral masks for V*TImode [PR94438]

The ix86_get_mask_mode hook uses int mask for 512-bit vectors or 128/256-bit
vectors with AVX512VL (that is correct), and only for V*[SD][IF]mode if not
AVX512BW (also correct), but with AVX512BW it would stop checking the
elem_size altogether and pretend the hw has masking support for V*TImode
etc., which it doesn't.  That can lead to various ICEs later on.

2020-04-08  Jakub Jelinek  <jakub@redhat.com>

	PR target/94438
	* config/i386/i386.c (ix86_get_mask_mode): Only use int mask for elem_size
	1, 2, 4 and 8.

	* gcc.target/i386/avx512bw-pr94438.c: New test.
	* gcc.target/i386/avx512vlbw-pr94438.c: New test.

(cherry picked from commit 8bf5faa9c463f0d53ffe835ba03d4502edfb959d)