[ubsan] Disable sigaction.cpp on x86_64 w/ ubsan-tsan

[Caslyn]

Test excluding x86_64

[Caslyn]

Restore RUN directive

[Caslyn]

@dvyukov - I think this could resolve the remaining error we're seeing on Fuchsia linux-x86_64 builds like this one: https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8775481122257091553/overview

This patch will expect the the UBSan-ThreadSanitizer-x86_64 :: TestCases/Misc/Linux/sigaction.cpp to fail as it does on that build. I think the fuchsia-x86_64-linux would have caught this, but it appears out of commission.

[dvyukov]

It only fails on Fuchsia Linux, right? (passed for me on normal Linux)
If so, please exclude on Fuchsia Linux.

[Caslyn]

Abandoning this attempt - and agree that it's too heavy handed. @mysterymath has taken the lead on debugging.

compiler-rt/test/ubsan/TestCases/Misc/Linux/sigaction.cpp

 // RUN: %clangxx -fsanitize=undefined -shared-libsan %s -o %t && %run %t 2>&1 | FileCheck %s
 
 // Ensure ubsan runtime/interceptors are lazily initialized if called early.
 
 // The test seems to segfault on aarch64 with tsan:
 // https://lab.llvm.org/buildbot/#/builders/179/builds/6662
 // Reason unknown, needs debugging.
-// XFAIL: target=aarch64{{.*}} && ubsan-tsan
+// XFAIL: target=aarch64{{(aarch64|x86_64).*}} && ubsan-tsan
 
 #include <assert.h>
 #include <signal.h>
 #include <stdio.h>
 
 __attribute__((constructor(0))) void ctor() {
   fprintf(stderr, "INIT\n");
   struct sigaction old;