[Bug testsuite/97688] check_vect doesn't detect AVX2 on zen

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97688

--- Comment #1 from Uroš Bizjak <ubizjak at gmail dot com> ---
AVX2 should be detected using __get_cpuid_count, because a sub-leaf needs to be
specified for leaf 7.