Sometimes report_fatal_error is called when there is not a handler function used...

Sometimes report_fatal_error is called when there is not a handler function used to fail gracefully. In that case, RunInterruptHandlers is called, which attempts to enter a critical section object. Ensure that the critical section is properly initialized so that this code functions properly, and tools like clang-tidy do not crash in Debug builds.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233282 91177308-0d34-0410-b5e6-96231b3b80d8