[Bug target/87853] _mm_cmpgt_epi8 broken with -funsigned-char

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87853

--- Comment #6 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Terry Guo from comment #5)
> What about a fix like below? I tested with bootstrap and regression test,
> there is no problem.

LGTM.