decoder: pull patch pending upstream inclusion for -fno-common toolchains

Without the change build fails on `staging` as:

    ld: decoder.o:(.bss.usageScreen+0x0): multiple definition of
      `usageScreen'; errors.o:(.bss.usageScreen+0x0): first defined here

pkgs/tools/security/decoder/default.nix

@@ -1,6 +1,7 @@
 { lib
 , stdenv
 , fetchFromGitHub
+, fetchpatch
 , openssl
 }:
 
@@ -15,6 +16,16 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-1sT1/iwtc2ievmLuNuooy9b14pTs1ZC5noDwzFelk7w=";
   };
 
+  patches = [
+    # Pull fix pending upstream inclusion for -fno-common toolchains:
+    #   https://github.com/PeterPawn/decoder/pull/29
+    (fetchpatch {
+      name = "fno-common.patch";
+      url = "https://github.com/PeterPawn/decoder/commit/843ac477c31108023d8008581bf91c5a3acc1859.patch";
+      sha256 = "sha256-rRylz8cxgNyPSqL/THdgEBpzcVx1K+xbjUn4PwP9Jn4=";
+    })
+  ];
+
   buildInputs = [
     openssl
   ];