* main.cxx (main): Always downgrade client-provided -p5 to -p4.
* stap-client (unpack_response): Sanitize stdout due to same.
* stap-server-connect.c: Eliminate a bunch of globals.
(handle_connection): Make things locals instead. Base tmp files
on $TMPDIR.
(spawn_and_wait): New helper function.
(handleRequest): New monster function to inline rest of old
stap-server-request.