Bug#1127626: libxsimd-dev: clang errors on ppc64el

[Drew Parsons]

Source: xsimd
Followup-For: Bug #1127626
X-Debbugs-Cc: debian-powerpc at lists.debian.org
User: debian-powerpc at lists.debian.org
Usertags: ppc64el
Control: severity -1 important

I've worked around the issue by skipping clang tests on ppc64el,
so lowering severity.

The problem should still be fixed not ignored though.