Make release_ts a bit more userfriendly

The -f option required manually *also* setting
the -w option. This is no longer required.

While at it, simplify the code by using the /proc interface.
rt_launch: add support for -q <priority>

This mirrors the option in rtspin.
Add tests for PCP/SRP ceiling blocking

Context: priority inheritance triggered a BUG_ON() in fp_common.c.
While at it, add a similar test for the SRP.
Include PID info in test failures

Useful for correlating test failures to events in traces.
Add basic locking support to rtspin

This is useful for testing locking protocol implementations (not
intended for benchmarking!), and also serves to document how to use
the LITMUS^RT locking API.