staging: ramster: cluster/messaging foundation

Copy cluster subdirectory from ocfs2.  These files implement
the basic cluster discovery, mapping, heartbeat / keepalive, and
messaging ("o2net") that ramster requires for internode communication.
Note: there are NO ramster-specific changes yet; this commit
does NOT pass checkpatch since the copied source files do not.

(Why copy?  This particular part of ocfs2 has never been broken out
for non-ocfs2 use before, some (small) changes are required for ramster
to use that code, and ramster is currently incompatible with real
ocfs2 anyway (requires !CONFIG_OCFS2_FS).  Before ramster can be promoted
out of staging, we will need to work with the ocfs2 maintainers to
see if the code interdependencies can be merged, but for now, for
staging, this seemed to be an expedient way to make use of the ocfs2
core cluster code while still incorporating necessary changes for ramster.)

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>