Revert "Add pretty printers for the NPTL lock types"

This reverts commit 62ce266b.

The change is not mature enough because it needs the following fixes:

1. Redirect test output to a file like other tests

2. Eliminate the need to use a .gdbinit because distributions will
   break without it.  I should have caught that but I was in too much
   of a hurry to get the patch in :/

3. Feature checking during configure to determine things like minimum
   required gdb version, python-pexpect version, etc. to make sure
   that tests work correctly.