debuginfo: Add timeout for LLDB tests.

If a test takes longer than 10 seconds it will be aborted now, which should prevent the build infrastructure from being blocked for a full hour if an LLDB freeze happens.

Since, as far as I've seen, the freezing happens very rarely and at random tests, we could also get fancy and automatically retry running the tests a few times if it was aborted due to a timeout. That would be quite nice actually.

cc @alexcrichton