treewide: use gnu toolchain for avr/arm-embedded

These packages should in theory work with our GCC toolchains, but
there are some definite breakages that need to be tracked down.
Comparing output of these to old gcc-arm-embedded is important.

Affected packages include:

- axolooti
- avrdudess
- opentx
- microscheme
- betaflight
- inav
- blackmagic
- simavr
- gnuk

pkgs/applications/misc/avrdudess/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, unzip, mono, avrbinutils, avrgcc, avrdude, gtk2, xdg_utils }:
+{ stdenv, fetchurl, unzip, mono, avrdude, gtk2, xdg_utils }:
 
 stdenv.mkDerivation rec {
   name = "avrdudess-2.2.20140102";
@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
     export LD_LIBRARY_PATH="${stdenv.lib.makeLibraryPath [gtk2 mono]}"
     # We need PATH from user env for xdg-open to find its tools, which
     # typically depend on the currently running desktop environment.
-    export PATH="${stdenv.lib.makeBinPath [ avrgcc avrbinutils avrdude xdg_utils ]}:\$PATH"
+    export PATH="${stdenv.lib.makeBinPath [ avrdude xdg_utils ]}:\$PATH"
 
     # avrdudess must have its resource files in its current working directory
     cd $out/avrdudess && exec ${mono}/bin/mono "$out/avrdudess/avrdudess.exe" "\$@"