i386: -mno-xsave should disable all relevant ISA flags [PR104462]

2022-02-09  Uroš Bizjak  <ubizjak@gmail.com>

gcc/ChangeLog:

	PR target/104462
	* common/config/i386/i386-common.cc (OPTION_MASK_ISA2_XSAVE_UNSET):
	Also include OPTION_MASK_ISA2_AVX2_UNSET.

gcc/testsuite/ChangeLog:

	PR target/104462
	* gcc.target/i386/pr104462.c: New test.