Mark internal_in as not strict, so that the construct "null::internal"

will throw an error, rather than possibly allowing someone to synthesize
a manual call to an internal-accepting function.  As of CVS HEAD and existing
releases, all such functions are either STRICT or careful about null inputs,
so there is no current security issue here.  But it seems like a good idea
to lock this down to protect against future mistakes.

In passing, similarly lock down trigger_in, language_handler_in, opaque_in,
and shell_in.  These are not believed to present any security risk, but
there's still no good reason to allow nulls of these types to be created.
I left the polymorphic pseudotypes (anyelement etc) alone, since a null
of one of those types doesn't seem to be a problem --- the worst you can
say about it is that it doesn't have an underlying non-polymorphic type.

If we were to make this change during normal development, we'd just
automatically bump catversion for a pg_proc.h change.  But since this doesn't
create a compatibility risk and isn't believed to be fixing a live bug, it
seems better not to force a catversion bump in late beta.

src/include/catalog/pg_proc.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.542 2009/04/09 17:39:48 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.543 2009/06/09 19:51:00 tgl Exp $
  *
  * NOTES
  *	  The script catalog/genbki.sh reads this file and generates .bki
@@ -3702,19 +3702,19 @@ DATA(insert OID = 2298 (  void_in			PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2278 "2
 DESCR("I/O");
 DATA(insert OID = 2299 (  void_out			PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2275 "2278" _null_ _null_ _null_ _null_ void_out _null_ _null_ _null_ ));
 DESCR("I/O");
-DATA(insert OID = 2300 (  trigger_in		PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2279 "2275" _null_ _null_ _null_ _null_ trigger_in _null_ _null_ _null_ ));
+DATA(insert OID = 2300 (  trigger_in		PGNSP PGUID 12 1 0 0 f f f f f i 1 0 2279 "2275" _null_ _null_ _null_ _null_ trigger_in _null_ _null_ _null_ ));
 DESCR("I/O");
 DATA(insert OID = 2301 (  trigger_out		PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2275 "2279" _null_ _null_ _null_ _null_ trigger_out _null_ _null_ _null_ ));
 DESCR("I/O");
-DATA(insert OID = 2302 (  language_handler_in	PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2280 "2275" _null_ _null_ _null_ _null_ language_handler_in _null_ _null_ _null_ ));
+DATA(insert OID = 2302 (  language_handler_in	PGNSP PGUID 12 1 0 0 f f f f f i 1 0 2280 "2275" _null_ _null_ _null_ _null_ language_handler_in _null_ _null_ _null_ ));
 DESCR("I/O");
 DATA(insert OID = 2303 (  language_handler_out	PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2275 "2280" _null_ _null_ _null_ _null_ language_handler_out _null_ _null_ _null_ ));
 DESCR("I/O");
-DATA(insert OID = 2304 (  internal_in		PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2281 "2275" _null_ _null_ _null_ _null_ internal_in _null_ _null_ _null_ ));
+DATA(insert OID = 2304 (  internal_in		PGNSP PGUID 12 1 0 0 f f f f f i 1 0 2281 "2275" _null_ _null_ _null_ _null_ internal_in _null_ _null_ _null_ ));
 DESCR("I/O");
 DATA(insert OID = 2305 (  internal_out		PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2275 "2281" _null_ _null_ _null_ _null_ internal_out _null_ _null_ _null_ ));
 DESCR("I/O");
-DATA(insert OID = 2306 (  opaque_in			PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2282 "2275" _null_ _null_ _null_ _null_ opaque_in _null_ _null_ _null_ ));
+DATA(insert OID = 2306 (  opaque_in			PGNSP PGUID 12 1 0 0 f f f f f i 1 0 2282 "2275" _null_ _null_ _null_ _null_ opaque_in _null_ _null_ _null_ ));
 DESCR("I/O");
 DATA(insert OID = 2307 (  opaque_out		PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2275 "2282" _null_ _null_ _null_ _null_ opaque_out _null_ _null_ _null_ ));
 DESCR("I/O");
@@ -3722,7 +3722,7 @@ DATA(insert OID = 2312 (  anyelement_in		PGNSP PGUID 12 1 0 0 f f f t f i 1 0 22
 DESCR("I/O");
 DATA(insert OID = 2313 (  anyelement_out	PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2275 "2283" _null_ _null_ _null_ _null_ anyelement_out _null_ _null_ _null_ ));
 DESCR("I/O");
-DATA(insert OID = 2398 (  shell_in			PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2282 "2275" _null_ _null_ _null_ _null_ shell_in _null_ _null_ _null_ ));
+DATA(insert OID = 2398 (  shell_in			PGNSP PGUID 12 1 0 0 f f f f f i 1 0 2282 "2275" _null_ _null_ _null_ _null_ shell_in _null_ _null_ _null_ ));
 DESCR("I/O");
 DATA(insert OID = 2399 (  shell_out			PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2275 "2282" _null_ _null_ _null_ _null_ shell_out _null_ _null_ _null_ ));
 DESCR("I/O");