Fix ALTER OPERATOR to update dependencies properly.

Fix an oversight in commit 321eed5f0f7563a0: replacing an operator's
selectivity functions needs to result in a corresponding update in
pg_depend.  We have a function that can handle that, but it was not
called by AlterOperator().

To fix this without enlarging pg_operator.h's #include list beyond
what clients can safely include, split off the function definitions
into a new file pg_operator_fn.h, similarly to what we've done for
some other catalog header files.  It's not entirely clear whether
any client-side code needs to include pg_operator.h, but it seems
prudent to assume that there is some such code somewhere.

src/include/catalog/pg_operator.h

@@ -23,8 +23,6 @@
 #define PG_OPERATOR_H
 
 #include "catalog/genbki.h"
-#include "catalog/objectaddress.h"
-#include "nodes/pg_list.h"
 
 /* ----------------
  *		pg_operator definition.  cpp turns this into
@@ -1826,19 +1824,4 @@ DESCR("delete array element");
 DATA(insert OID = 3287 (  "#-"	   PGNSP PGUID b f f 3802 1009 3802 0 0 jsonb_delete_path - - ));
 DESCR("delete path");
 
-/*
- * function prototypes
- */
-extern ObjectAddress OperatorCreate(const char *operatorName,
-			   Oid operatorNamespace,
-			   Oid leftTypeId,
-			   Oid rightTypeId,
-			   Oid procedureId,
-			   List *commutatorName,
-			   List *negatorName,
-			   Oid restrictionId,
-			   Oid joinId,
-			   bool canMerge,
-			   bool canHash);
-
 #endif   /* PG_OPERATOR_H */

src/include/catalog/pg_operator_fn.h

@@ -0,0 +1,34 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_operator_fn.h
+*	 prototypes for functions in catalog/pg_operator.c
+ *
+ *
+ * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/catalog/pg_operator_fn.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PG_OPERATOR_FN_H
+#define PG_OPERATOR_FN_H
+
+#include "catalog/objectaddress.h"
+#include "nodes/pg_list.h"
+
+extern ObjectAddress OperatorCreate(const char *operatorName,
+			   Oid operatorNamespace,
+			   Oid leftTypeId,
+			   Oid rightTypeId,
+			   Oid procedureId,
+			   List *commutatorName,
+			   List *negatorName,
+			   Oid restrictionId,
+			   Oid joinId,
+			   bool canMerge,
+			   bool canHash);
+
+extern ObjectAddress makeOperatorDependencies(HeapTuple tuple, bool isUpdate);
+
+#endif   /* PG_OPERATOR_FN_H */