pgsql: Fix pg_dump to ensure that a comment on a table CHECK constraint

Log Message:
-----------
Fix pg_dump to ensure that a comment on a table CHECK constraint cannot
be emitted too soon.  The previous code got this right in the case where
the CHECK was emitted as a separate ALTER TABLE command, but not in the
case where the CHECK is emitted right in CREATE TABLE.  Per report from
Slawomir Sudnik.

Note: this code is pretty ugly; it'd perhaps be better to treat comments
as independently sortable dump objects.  That'd be much too invasive a
change for RC time though.

Modified Files:
--------------
    pgsql/src/bin/pg_dump:
        pg_dump.c (r1.394 -> r1.395)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_dump.c.diff?r1=1.394&r2=1.395)