[compiler-rt] [test] Mark dfsan tests XFAIL on glibc-2.37

Mark the two dfsan tests that are known to be broken on glibc-2.37
as XFAIL, to make the test suite start passing on Gentoo again.

Bug: https://github.com/llvm/llvm-project/issues/60678

Differential Revision: https://reviews.llvm.org/D148496