Fixed implicit declaration of fopen()

After upgrading to curl 8.16.0 we got

```
altsvc.c: In function 'altsvc_load':
altsvc.c:230:8: error: implicit declaration of function 'fopen' [-Werror=implicit-function-declaration]
   fp = fopen(file, FOPEN_READTEXT);
        ^~~~~
```

on AIX 7.1. The header stdio.h is probably included indirectly on all
other platforms.

Signed-off-by: Lars Erik Wik <lars.erik.wik@northern.tech>

Author: larsewi

deps-packaging/libcurl/cfbuild-libcurl.spec

@@ -46,6 +46,11 @@ mkdir -p %{_builddir}
 
 %build
 
+# Implicit declaration of function 'fopen' after upgrading to curl 8.16.0.
+# This is only needed for AIX 7.1.
+# However, it does not hurt to apply it for every one.
+patch -p1 < %{_topdir}/SOURCES/implicit-decl-fopen.patch
+
 make
 
 %install

deps-packaging/libcurl/implicit-decl-fopen.patch

@@ -0,0 +1,12 @@
+diff -ruN curl-8.16.0/lib/altsvc.c curl-8.16.0-modified/lib/altsvc.c
+--- curl-8.16.0/lib/altsvc.c	2025-09-10 07:43:43.000000000 +0200
++++ curl-8.16.0-modified/lib/altsvc.c	2025-09-23 12:31:02.073633250 +0200
+@@ -27,6 +27,8 @@
+  */
+ #include "curl_setup.h"
+ 
++#include <stdio.h> /* fopen() */
++
+ #if !defined(CURL_DISABLE_HTTP) && !defined(CURL_DISABLE_ALTSVC)
+ #include <curl/curl.h>
+ #include "urldata.h"