pgsql: Cleanup of GiST extensions in contrib/: now that we always invoke

Log Message:
-----------
Cleanup of GiST extensions in contrib/: now that we always invoke GiST
methods in a short-lived memory context, there is no need for GiST methods
to do their own manual (and error-prone) memory management.

Modified Files:
--------------
pgsql/contrib/btree_gist:
btree_bit.c (r1.4 -> r1.5)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_bit.c.diff?r1=1.4&r2=1.5)
btree_bytea.c (r1.4 -> r1.5)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_bytea.c.diff?r1=1.4&r2=1.5)
btree_numeric.c (r1.4 -> r1.5)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_numeric.c.diff?r1=1.4&r2=1.5)
btree_text.c (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_text.c.diff?r1=1.5&r2=1.6)
btree_time.c (r1.6 -> r1.7)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_time.c.diff?r1=1.6&r2=1.7)
btree_ts.c (r1.7 -> r1.8)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_ts.c.diff?r1=1.7&r2=1.8)
btree_utils_num.c (r1.6 -> r1.7)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_utils_num.c.diff?r1=1.6&r2=1.7)
btree_utils_var.c (r1.8 -> r1.9)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/btree_utils_var.c.diff?r1=1.8&r2=1.9)
pgsql/contrib/cube:
cube.c (r1.19 -> r1.20)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/cube/cube.c.diff?r1=1.19&r2=1.20)
pgsql/contrib/ltree:
_ltree_gist.c (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/_ltree_gist.c.diff?r1=1.10&r2=1.11)
ltree_gist.c (r1.8 -> r1.9)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/ltree_gist.c.diff?r1=1.8&r2=1.9)
pgsql/contrib/pg_trgm:
trgm_gist.c (r1.2 -> r1.3)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_trgm/trgm_gist.c.diff?r1=1.2&r2=1.3)
pgsql/contrib/rtree_gist:
rtree_gist.c (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/rtree_gist/rtree_gist.c.diff?r1=1.10&r2=1.11)
pgsql/contrib/seg:
seg.c (r1.12 -> r1.13)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/seg/seg.c.diff?r1=1.12&r2=1.13)
pgsql/contrib/tsearch:
gistidx.c (r1.8 -> r1.9)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch/gistidx.c.diff?r1=1.8&r2=1.9)
pgsql/contrib/tsearch2:
gistidx.c (r1.6 -> r1.7)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/gistidx.c.diff?r1=1.6&r2=1.7)