lint: support __float128

Needed by libquadmath.

Author: rillig

tests/usr.bin/xlint/lint1/gcc.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: gcc.c,v 1.6 2025/07/31 17:30:52 rillig Exp $	*/
+/*	$NetBSD: gcc.c,v 1.7 2026/01/20 23:46:36 rillig Exp $	*/
 # 3 "gcc.c"
 
 /*
@@ -126,3 +126,5 @@ atomic_functions(void)
 	/* expect+1: warning: conversion from 'unsigned long long' to 'char' may lose accuracy [132] */
 	c = __atomic_exchange_n(pv, 0, 0);
 }
+
+__float128 f128 = 0.0;

usr.bin/xlint/lint1/main1.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: main1.c,v 1.84 2024/09/24 19:58:06 rillig Exp $	*/
+/*	$NetBSD: main1.c,v 1.85 2026/01/20 23:46:36 rillig Exp $	*/
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID)
-__RCSID("$NetBSD: main1.c,v 1.84 2024/09/24 19:58:06 rillig Exp $");
+__RCSID("$NetBSD: main1.c,v 1.85 2026/01/20 23:46:36 rillig Exp $");
 #endif
 
 #include <sys/types.h>
@@ -87,6 +87,7 @@ gcc_builtins(void)
 	/* https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html */
 	static const char builtins[] =
 	    "typedef typeof(sizeof(0)) __lint_size_t;\n"
+	    "typedef long double __float128;\n"
 
 	    "void *alloca(__lint_size_t);\n"
 	    "void *__builtin_alloca(__lint_size_t);\n"