AddressSanitizer tests fail for powerpc64

AddressSanitizer used to work for PowerPC some time ago, but at this time the tests are broken. We have an ASAN buildbot running to track the status of these tests; see http://lab.llvm.org:8011/builders/sanitizer-ppc64-linux1/. Currently the buildbot stops with this failure: FAIL: SanitizerCommon-asan :: Linux/ptrace.cc (1 of 12) ******************** TEST 'SanitizerCommon-asan :: Linux/ptrace.cc' FAILED ******************** Script: -- /home/buildbots/sanitizerslave1/sanitizer-ppc64-1/build/clang_build/./bin/clang --driver-mode=g++ -gline-tables-only -fsanitize=address -O0 /home/buildbots/sanitizerslave1/sanitizer-ppc64-1/build/llvm/projects/compiler-rt/test/sanitizer_common/TestCases/Linux/ptrace.cc -o /home/buildbots/sanitizerslave1/sanitizer-ppc64-1/build/clang_build/projects/compiler-rt/test/sanitizer_common/asan/Linux/Output/ptrace.cc.tmp && /home/buildbots/sanitizerslave1/sanitizer-ppc64-1/build/clang_build/projects/compiler-rt/test/sanitizer_common/asan/Linux/Output/ptrace.cc.tmp -- Exit Code: 1 Command Output (stderr): -- /home/buildbots/sanitizerslave1/sanitizer-ppc64-1/build/llvm/projects/compiler-rt/test/sanitizer_common/TestCases/Linux/ptrace.cc:21:5: error: unknown type name 'user_regs_struct' user_regs_struct regs; ^ /home/buildbots/sanitizerslave1/sanitizer-ppc64-1/build/llvm/projects/compiler-rt/test/sanitizer_common/TestCases/Linux/ptrace.cc:28:5: error: unknown type name 'user_fpregs_struct' user_fpregs_struct fpregs; ^ 2 errors generated. Presumably this requires a simple fix. However, we know there are more pervasive problems from earlier investigations, where it appeared that some endian issues exist in the ASAN code. This bug should be kept open until all of the ASAN test cases pass successfully for powerpc64-unknown-linux-gnu and the buildbot status is green and stable.