redhat: package new file include/opr/lock.h

redhat: package new file include/opr/lock.h

Commit 792dd44ac57032a3f2a4743c83c8a0208a08ecec added the
installation of include/opr/lock.h, but the rpm spec fails
to pick it up, making rpm builds fail. Add the new file
to the files list for the -devel package.

FIXES 134579

Change-Id: I998f48bd88308d81779dd775b322590eda75d5c8
Reviewed-on: https://gerrit.openafs.org/13238
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>