Add a tool to find lock ID numbers

Add a tool to find lock ID numbers

This adds a Perl program, src/afs/findlocks, which grovels through the
kernel module source tree, finds every location where a lock is obtained,
and produces an index of lock site ID numbers.  This can be used to find
a lock when debugging, or when picking a new number.

Run it as ./src/afs/findlocks src/afs

Change-Id: I7fdcfb807a92dbb1938a0c37637e9122b52addd7
Reviewed-on: http://gerrit.openafs.org/9982
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Simon Wilkinson <simonxwilkinson@gmail.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>