pgsql: Move plpgsql DEBUG from DEBUG2 to DEBUG1 because it is a

Log Message:
-----------
Move plpgsql DEBUG from DEBUG2 to DEBUG1 because it is a user-requested
DEBUG.

Fix a few places where DEBUG1 crept in that should have been DEBUG2.

Modified Files:
--------------
    pgsql/src/backend/access/transam:
        slru.c (r1.23 -> r1.24)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/slru.c.diff?r1=1.23&r2=1.24)
        xlog.c (r1.180 -> r1.181)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c.diff?r1=1.180&r2=1.181)
    pgsql/src/backend/libpq:
        hba.c (r1.136 -> r1.137)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/hba.c.diff?r1=1.136&r2=1.137)