[Support/CrashRecoveryContext] Make sure CrashRecoveryContext does not clear the thread-local "CurrentContext"
in the "parent" thread, when we are using CrashRecoveryContext::RunSafelyOnThread.
When using CrashRecoveryContext::RunSafelyOnThread, we would set a CrashRecoveryContextImpl* to a thread-local variable
for the "child" thread, but CrashRecoveryContext would erroneously clear it in the "parent" thread.
The result was that if CrashRecoveryContext::RunSafelyOnThread was called again in the "child" thread it would mess up
crash-recovery for its parent.
A test for this will be added in the clang repository.
rdar://
14204560
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184380
91177308-0d34-0410-b5e6-
96231b3b80d8