[PATCH v8] Add pretty printers for the NPTL lock types

[Martin Galvan]

Update: Pedro's suggestion worked fine, so now the unit tests should
work with newer versions of gdb as well. I've also added diagnostic
messages for when the unit tests fail, including the command that was
issued to gdb, its response, and the expected pattern. Hopefully I'll
have a new version ready before/through the weekend.

Sid, could you please tell me which command are you using to check the
libraries, so I'm sure we're on the same page?