[powerpc] deactivate ManyThreadsTest asan test on powerpc64

This test case occassionally hangs when run on powerpc.  This is also a
problem on AArch64 (see https://bugs.llvm.org/show_bug.cgi?id=24389).
Reactivate this when the problem is fixed.

This could also be related to the same problem as with the tests
ThreadedOneSizeMallocStressTest, ThreadedMallocStressTest, and several
others that do not run reliably on powerpc.

llvm-svn: 298873

Author: BillSeurer

compiler-rt/lib/asan/tests/asan_test.cc

@@ -337,8 +337,9 @@ void *ManyThreadsWorker(void *a) {
   return 0;
 }
 
-#if !defined(__aarch64__)
+#if !defined(__aarch64__) && !defined(__powerpc64__)
 // FIXME: Infinite loop in AArch64 (PR24389).
+// FIXME: Also occasional hang on powerpc.  Maybe same problem as on AArch64?
 TEST(AddressSanitizer, ManyThreadsTest) {
   const size_t kNumThreads =
       (SANITIZER_WORDSIZE == 32 || ASAN_AVOID_EXPENSIVE_TESTS) ? 30 : 1000;