Fix pg_get_functiondef() to print a function's LEAKPROOF property.

Seems to have been an oversight in the original leakproofness patch.
Per report and patch from Jeevan Chalke.

In passing, prettify some awkward leakproof-related code in AlterFunction.

src/backend/commands/functioncmds.c

@@ -1190,11 +1190,11 @@ AlterFunction(AlterFunctionStmt *stmt)
 		procForm->prosecdef = intVal(security_def_item->arg);
 	if (leakproof_item)
 	{
-		if (intVal(leakproof_item->arg) && !superuser())
+		procForm->proleakproof = intVal(leakproof_item->arg);
+		if (procForm->proleakproof && !superuser())
 			ereport(ERROR,
 					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 				  errmsg("only superuser can define a leakproof function")));
-		procForm->proleakproof = intVal(leakproof_item->arg);
 	}
 	if (cost_item)
 	{

src/backend/utils/adt/ruleutils.c

@@ -1985,6 +1985,8 @@ pg_get_functiondef(PG_FUNCTION_ARGS)
 		appendStringInfoString(&buf, " STRICT");
 	if (proc->prosecdef)
 		appendStringInfoString(&buf, " SECURITY DEFINER");
+	if (proc->proleakproof)
+		appendStringInfoString(&buf, " LEAKPROOF");
 
 	/* This code for the default cost and rows should match functioncmds.c */
 	if (proc->prolang == INTERNALlanguageId ||