The debugger relies on hooks into the interpreter to gain control of threads. If a thread is looping in translated code, though, it will never enter the interpreter. Take advantage of the existing surprise checks emitted on back-branches to pop out of translated code back to the interpreter when trying to interrupt threads due to a Ctrl-C from the client.
Also modified TestDebuggerJit to ensure that the thread executing the infinite loop has time to settle into looping in TC's. The signal to interrupt the server is historically fast enough to get there before one of the translations is made. Added a reasonable delay which caused the test to fail deterministically on my machine before the fix.
Mike Magruder