[compiler-rt] Reapply "[sanitizer_common] AND signals in BlockSignals instead of deleting (#113443)" for non-Android Linux only (PR #115790)

[Thurston Dang via llvm-commits]

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@@ -181,9 +178,7 @@ static void KeepUnblocked(__sanitizer_sigset_t &newset,
 void BlockSignals(__sanitizer_sigset_t *oldset) {
   __sanitizer_sigset_t currentset;
 #  if !SANITIZER_ANDROID
-  // FIXME: SetSigProcMask and pthread_sigmask cause mysterious failures
-  // See also: comment in KeepUnblocked().
-  // In the meantime, we prefer to sometimes incorrectly unblock signals.
+  // FIXME: SetSigProcMask cause mysterious failures on Android
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thurstond wrote:

Filed https://github.com/google/sanitizers/issues/1816 and updated the FIXMEs

https://github.com/llvm/llvm-project/pull/115790