pgsql: Add explicit casts between int4 and boolean.

Log Message:
-----------
Add explicit casts between int4 and boolean. Patch from Sean Chittenden,
editorializing by Neil Conway. Catalog version bumped.

Modified Files:
--------------
pgsql/src/backend/utils/adt:
int.c (r1.64 -> r1.65)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/int.c.diff?r1=1.64&r2=1.65)
pgsql/src/include/catalog:
catversion.h (r1.255 -> r1.256)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.255&r2=1.256)
pg_cast.h (r1.17 -> r1.18)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_cast.h.diff?r1=1.17&r2=1.18)
pg_proc.h (r1.350 -> r1.351)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h.diff?r1=1.350&r2=1.351)
pgsql/src/include/utils:
builtins.h (r1.252 -> r1.253)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/builtins.h.diff?r1=1.252&r2=1.253)