[TSan] Do not run cond_cancel.c test on ppc64.
After r319004, the expected failure on ppc64 manifests as an infinite
loop.
// (defined in sanitizer_thread_registry.cc). It might seem a bug on glibc,
// however the same version GLIBC-2.17 will not make fail the test on
// powerpc64 BE (VMA=46)
-// XFAIL: powerpc64-unknown-linux-gnu
+// UNSUPPORTED: powerpc64-unknown-linux-gnu
#include "test.h"
