pgsql: Bug fixes for GiST crash recovery.

Log Message:
-----------
Bug fixes for GiST crash recovery.
- add forgotten check of lsn for insert completion
- remove level of pages: hard to check in recovery
- some cleanups

Modified Files:
--------------
    pgsql/src/backend/access/gist:
        gist.c (r1.124 -> r1.125)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gist.c.diff?r1=1.124&r2=1.125)
        gistutil.c (r1.4 -> r1.5)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistutil.c.diff?r1=1.4&r2=1.5)
        gistvacuum.c (r1.5 -> r1.6)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistvacuum.c.diff?r1=1.5&r2=1.6)
        gistxlog.c (r1.5 -> r1.6)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistxlog.c.diff?r1=1.5&r2=1.6)
    pgsql/src/include/access:
        gist.h (r1.48 -> r1.49)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/gist.h.diff?r1=1.48&r2=1.49)
        gist_private.h (r1.6 -> r1.7)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/gist_private.h.diff?r1=1.6&r2=1.7)