Fix the volatility marking of textanycat() and anytextcat(): they were marked

immutable, but that is wrong in general because the cast from the polymorphic
argument to text could be stable or even volatile.  Mark them volatile for
safety.  In the typical case where the cast isn't volatile, the planner will
deduce the correct expression volatility after inlining the function, so
performance is not lost.  The just-committed fix in CREATE INDEX also ensures
this won't break any indexing cases that ought to be allowed.

Per discussion, I'm not bumping catversion for this change, as it doesn't
seem critical enough to force an initdb on beta testers.

src/include/catalog/pg_proc.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.570 2010/02/26 02:01:21 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.571 2010/05/27 16:20:11 tgl Exp $
  *
  * NOTES
  *	  The script catalog/genbki.pl reads this file and generates .bki
@@ -3137,9 +3137,9 @@ DESCR("adjust time precision");
 DATA(insert OID = 1969 (  timetz		   PGNSP PGUID 12 1 0 0 f f f t f i 2 0 1266 "1266 23" _null_ _null_ _null_ _null_ timetz_scale _null_ _null_ _null_ ));
 DESCR("adjust time with time zone precision");
 
-DATA(insert OID = 2003 (  textanycat	   PGNSP PGUID 14 1 0 0 f f f t f i 2 0 25 "25 2776" _null_ _null_ _null_ _null_ "select $1 || $2::pg_catalog.text" _null_ _null_ _null_ ));
+DATA(insert OID = 2003 (  textanycat	   PGNSP PGUID 14 1 0 0 f f f t f v 2 0 25 "25 2776" _null_ _null_ _null_ _null_ "select $1 || $2::pg_catalog.text" _null_ _null_ _null_ ));
 DESCR("concatenate");
-DATA(insert OID = 2004 (  anytextcat	   PGNSP PGUID 14 1 0 0 f f f t f i 2 0 25 "2776 25" _null_ _null_ _null_ _null_ "select $1::pg_catalog.text || $2" _null_ _null_ _null_ ));
+DATA(insert OID = 2004 (  anytextcat	   PGNSP PGUID 14 1 0 0 f f f t f v 2 0 25 "2776 25" _null_ _null_ _null_ _null_ "select $1::pg_catalog.text || $2" _null_ _null_ _null_ ));
 DESCR("concatenate");
 
 DATA(insert OID = 2005 (  bytealike		   PGNSP PGUID 12 1 0 0 f f f t f i 2 0 16 "17 17" _null_ _null_ _null_ _null_ bytealike _null_ _null_ _null_ ));