fs: dlm: rename stub to local message flag

This patch renames DLM_IFL_STUB_MS to DLM_IFL_LOCAL_MS flag. The
DLM_IFL_STUB_MS flag is somewhat misnamed, it means the dlm message is
used for local message transfer only. It is used by recovery to resolve
lock states if a node got fenced.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>