tsan: disable ignore_lib4.cc test on powerpc64 and aarch64

Fails on bots:
http://lab.llvm.org:8011/builders/clang-ppc64be-linux/builds/1555/steps/ninja%20check%201/logs/FAIL%3A%20ThreadSanitizer-powerpc64%3A%3A%20ignore_lib4.cc
http://lab.llvm.org:8011/builders/sanitizer-ppc64be-linux/builds/725/steps/ninja%20check-tsan/logs/stdio
http://lab.llvm.org:8011/builders/clang-cmake-aarch64-full/builds/1468/steps/ninja%20check%202/logs/FAIL%3A%20ThreadSanitizer-aarch64%3A%3A%20ignore_lib4.cc
http://lab.llvm.org:8011/builders/clang-native-aarch64-full/builds/2787/steps/ninja%20check%202/logs/FAIL%3A%20ThreadSanitizer-aarch64%3A%3A%20ignore_lib4.cc

llvm-svn: 261728
1 file changed