dirt: pull fix pending upstream inclusion for -fno-common toolchains

Without the change build fails on -fno-common toolchains like upstream
gcc-10:

    ld: audio.o:/home/slyfox/dev/git/Dirt/audio.h:55: multiple definition of
      `delays'; dirt.o:/home/slyfox/dev/git/Dirt/audio.h:55: first defined here

pkgs/applications/audio/dirt/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, libsndfile, libsamplerate, liblo, libjack2 }:
+{ lib, stdenv, fetchFromGitHub, fetchpatch, libsndfile, libsamplerate, liblo, libjack2 }:
 
 stdenv.mkDerivation {
   pname = "dirt";
@@ -10,6 +10,15 @@ stdenv.mkDerivation {
     sha256 = "13adglk2d31d7mswfvi02b0rjdhzmsv11cc8smhidmrns3f9s96n";
     fetchSubmodules = true;
   };
+  patches = [
+    # Pull patch pending upstream inclusion for upstream gcc-10 support:
+    #  https://github.com/tidalcycles/Dirt/pull/65
+    (fetchpatch {
+      name = "fno-common.patch";
+      url = "https://github.com/tidalcycles/Dirt/commit/43fd267745d486228c4185b4fcbd7d9fbc362cc2.patch";
+      sha256 = "08r34ylzs31wwf0la995pb149ccq0vr7qg4792pkhca57zi0bff8";
+    })
+  ];
   buildInputs = [ libsndfile libsamplerate liblo libjack2 ];
   postPatch = ''
     sed -i "s|./samples|$out/share/dirt/samples|" dirt.c