zend_ast: Remove unused ZEND_AST_EXIT (#17417)

This AST node is no longer used since `exit()` was made a real function in
GH-13483.

Author: TimWolla

Zend/zend_ast.c

@@ -2150,13 +2150,6 @@ static ZEND_COLD void zend_ast_export_ex(smart_str *str, zend_ast *ast, int prio
 			break;
 		case ZEND_AST_CLONE:
 			PREFIX_OP("clone ", 270, 271);
-		case ZEND_AST_EXIT:
-			if (ast->child[0]) {
-				FUNC_OP("exit");
-			} else {
-				APPEND_STR("exit");
-			}
-			break;
 		case ZEND_AST_PRINT:
 			PREFIX_OP("print ", 60, 61);
 		case ZEND_AST_INCLUDE_OR_EVAL:

Zend/zend_ast.h

@@ -88,7 +88,6 @@ enum _zend_ast_kind {
 	ZEND_AST_SILENCE,
 	ZEND_AST_SHELL_EXEC,
 	ZEND_AST_CLONE,
-	ZEND_AST_EXIT,
 	ZEND_AST_PRINT,
 	ZEND_AST_INCLUDE_OR_EVAL,
 	ZEND_AST_UNARY_OP,