cgui: fix build with gcc15

pkgs/by-name/cg/cgui/fix-gcc15.patch

@@ -0,0 +1,15 @@
+diff --git a/examples/25viewer.c b/examples/25viewer.c
+index 37e4585..a0328f0 100644
+--- a/examples/25viewer.c
++++ b/examples/25viewer.c
+@@ -10,8 +10,9 @@
+ 
+ static const char *fname; /* stores name of file to open */
+ 
+-void quit()
++void quit(void *data)
+ {
++   (void)data;
+    exit(0);
+ }
+ 

pkgs/by-name/cg/cgui/package.nix

@@ -17,6 +17,10 @@ stdenv.mkDerivation (finalAttrs: {
     sha256 = "1pp1hvidpilq37skkmbgba4lvzi01rasy04y0cnas9ck0canv00s";
   };
 
+  patches = [
+    ./fix-gcc15.patch
+  ];
+
   buildInputs = [
     texinfo
     allegro