This reverts commit e7ccaf5f.

Before commit e7ccaf5f, every time a resource group glock was
dequeued by gfs2_glock_dq(), it was added to the glock LRU list even
though the glock was still referenced by the resource group and could
never be evicted, anyway.  Commit e7ccaf5f added a GLOF_LRU hack to
avoid that overhead for resource group glocks, and that hack was since
adopted for some other types of glocks as well.

We now no longer add glocks to the glock LRU list while they are still
referenced.  This solves the underlying problem, and obsoletes the
GLOF_LRU hack.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
(cherry picked from commit 3e5257c810cba91e274d07f3db5cf013c7c830be)