Further to https://github.com/llvm/llvm-project/pull/209306, test a case where a signal handler is a Virtual API function triggered synchronously while the VAPI is not active. Resuming an ancestor context of the signal frame should call the VAPI return glue. --------- Assisted-by: IBM Bob (cherry picked from commit dbaabbc920fcd60aeed5109c3c6353830e7605c5)