bug#70484: Fix compatibility of build-aux/make-info-dir script

[Ulrich Mueller <ulm@gentoo.org>]

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Attached patch fixes the problem for me. It applies cleanly to both
emacs-29 and master.

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From cb490ee7a8365c6375dc6c7a5f6d8202ab381219 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ulrich=20M=C3=BCller?= <ulm@gentoo.org>
Date: Tue, 23 Apr 2024 07:37:17 +0200
Subject: [PATCH] * build-aux/make-info-dir: Avoid bashism (bug#70484).

---
 build-aux/make-info-dir | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/build-aux/make-info-dir b/build-aux/make-info-dir
index e5f4972902f..631fe533e69 100755
--- a/build-aux/make-info-dir
+++ b/build-aux/make-info-dir
@@ -33,7 +33,8 @@
 
 ## Header contains non-printing characters, so this is more
 ## reliable than using awk.
-cat <"${1?}" || exit
+test $# -ge 2 || exit 1
+cat <"$1"
 shift
 
 exec "${AWK-awk}" '
@@ -101,4 +102,4 @@       detexinfo()
       if (data[dircat])
         printf "\n%s\n%s", topic[dircat], data[dircat]
   }
-' "${@?}"
+' "$@"
-- 
2.44.0