pgsql: Set pg_am.amstrategies to zero for index AMs that don't have

Log Message:
-----------
Set pg_am.amstrategies to zero for index AMs that don't have fixed
operator strategy numbers, ie, GiST and GIN. This is almost cosmetic
enough to not need a catversion bump, but since the opr_sanity regression
test has to change in sync with the catalog entry, I figured I'd better
do one.

Modified Files:
--------------
pgsql/doc/src/sgml:
catalogs.sgml (r2.137 -> r2.138)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/catalogs.sgml.diff?r1=2.137&r2=2.138)
pgsql/src/backend/commands:
opclasscmds.c (r1.49 -> r1.50)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/opclasscmds.c.diff?r1=1.49&r2=1.50)
pgsql/src/backend/optimizer/util:
plancat.c (r1.127 -> r1.128)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/plancat.c.diff?r1=1.127&r2=1.128)
pgsql/src/include/catalog:
catversion.h (r1.362 -> r1.363)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.362&r2=1.363)
pg_am.h (r1.46 -> r1.47)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_am.h.diff?r1=1.46&r2=1.47)
pgsql/src/test/regress/expected:
opr_sanity.out (r1.67 -> r1.68)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/opr_sanity.out.diff?r1=1.67&r2=1.68)
pgsql/src/test/regress/sql:
opr_sanity.sql (r1.53 -> r1.54)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/opr_sanity.sql.diff?r1=1.53&r2=1.54)