avr-gcc: set meta.platforms = linux

So that hydra will build it and add it to the binary channel.

pkgs/development/misc/avr-gcc-with-avr-libc/default.nix

@@ -78,10 +78,11 @@ stdenv.mkDerivation {
     '';
   };
 
-  meta = { 
+  meta = with stdenv.lib; {
       description = "AVR developement environment including binutils, avr-gcc and avr-libc";
       # I've tried compiling the packages separately.. too much hassle. This just works. Fine.
       license =  ["GPL" "LGPL"]; # see single packages ..
       homepage = []; # dito
+      platforms = platforms.linux;
   };
 }