cbatticon: Fix build by removing -Wno-format

This conflicts with -Werror=format-security and the build doesn't have
any format security problems, so -Wno-format IMHO shouldn't be there in
the first place.

Signed-off-by: aszlig <aszlig@nix.build>
Cc: @domenkozar

pkgs/applications/misc/cbatticon/default.nix

@@ -12,6 +12,10 @@ stdenv.mkDerivation rec {
     sha256 = "16g26vin1693dbdr9qsnw36fdchx394lp79gvp7gcbw0w1ny9av6";
   };
 
+  patchPhase = ''
+    sed -i -e 's/ -Wno-format//g' Makefile
+  '';
+
   makeFlags = "PREFIX=$(out)";
 
   nativeBuildInputs = [ pkgconfig gettext ];