On process exit, it was possible that the filesystem timestamp
resolution measurement left behind .probe files or even a lock file
for the jgit.config.
Ensure the SAVE_RUNNER is shut down when the process exits (via
System.exit() or otherwise). Move lf.lock() into the try-finally
block when saving the config file.
Delete .probe files on JVM shutdown -- they are created in daemon
threads that may terminate abruptly, not executing the "finally"
clause that normally removes these files.
Bug: 579445
Change-Id: Ie27aca1fdaddfa487ebe072c3913d78355910df8
88d5f51e61