pgsql: Put back another improperly-removed #include.
Log Message:
-----------
Put back another improperly-removed #include.
Modified Files:
--------------
    pgsql/src/backend/storage/lmgr:
        lwlock.c (r1.44 -> r1.45)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/lwlock.c.diff?r1=1.44&r2=1.45)