ProcedureCreate neglected to record dependencies on default expressions.

Thus, an object referenced in a default expression could be dropped while
the function remained present.  This was unaccountably missed in the
original patch to add default parameters for functions.  Reported by
Pavel Stehule.

src/backend/catalog/pg_proc.c

@@ -598,6 +598,11 @@ ProcedureCreate(const char *procedureName,
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 	}
 
+	/* dependency on parameter default expressions */
+	if (parameterDefaults)
+		recordDependencyOnExpr(&myself, (Node *) parameterDefaults,
+							   NIL, DEPENDENCY_NORMAL);
+
 	/* dependency on owner */
 	if (!is_update)
 		recordDependencyOnOwner(ProcedureRelationId, retval, proowner);