Un-XFAIL two tests with Clang > 10

SVN r343917 fixed this for in-tree clang, but when building with a newer
out-of-tree clang the test was still marked as XFAIL.

Reviewed By: dim
Differential Revision: https://reviews.freebsd.org/D28390

(cherry picked from commit 83ff5d5d98cbcf9b66dccd70022358aec8918a14)