mdk3-master: unbreak on GCC-14

pkgs/by-name/md/mdk3-master/package.nix

···
 
   runtimeDependencies = [ wirelesstools ];
 
+  # fix
+  env.NIX_CFLAGS_COMPILE = "-Wno-error=incompatible-pointer-types";
+
   installPhase = ''
     runHook preInstall
     make -C osdep install