autoconf: doc: fix texinfo location reports

https://github.com/libsdl-org/autoconf/commit/e48b65f81136a2214d9b6ea1bfe7ba4b1a48f346

From e48b65f81136a2214d9b6ea1bfe7ba4b1a48f346 Mon Sep 17 00:00:00 2001
From: Eric Blake <[EMAIL REDACTED]>
Date: Tue, 17 Jul 2012 12:02:12 -0600
Subject: [PATCH] doc: fix texinfo location reports

Otherwise, newer texinfo parses this line as a line directive, and
any error later in the file will claim to be from "conftest.c" instead
of "autoconf.texi".

* doc/autoconf.texi (Generating Sources): Avoid confusing newer
texinfo into thinking we had a line directive.
Reported by Stefano Lattarini, fix suggested by Patrice Dumas.
(cherry picked from commit 8c8522f1c5c8362ec683b5464e99a95bc735677f)
---
 doc/autoconf.texi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 393e38f2..14de7b01 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -9154,7 +9154,7 @@ on a system with @command{gcc} installed, results in:
 @example
 @c If you change this example, adjust tests/compile.at:AC_LANG_SOURCE example.
 @dots{}
-# 1 "conftest.c"
+@asis{#} 1 "conftest.c"
 
 #define PACKAGE_NAME "Hello"
 #define PACKAGE_TARNAME "hello"
@@ -9199,7 +9199,7 @@ on a system with @command{gcc} installed, results in:
 @example
 @c If you change this example, adjust tests/compile.at:AC_LANG_PROGRAM example.
 @dots{}
-# 1 "conftest.c"
+@asis{#} 1 "conftest.c"
 
 #define PACKAGE_NAME "Hello"
 #define PACKAGE_TARNAME "hello"