Branch b1_4

Branch b1_4
Use the existing b1_4 ldlm_flock struct, but make the pid types well defined
sizes (even though the blocking_pid is not sent over the wire, it is a
historical accident that it is inside the ldlm_flock policy data)  and add
swabbing for the extent.gid field (which in b_cray overlapped with flock.pid
so they were swabbed at the same time).
b=6931
r=phil