harvid: fix pending upstream inclusion to support parallel builds

Without the change parallel build fails as:

    make -C src
    make[1]: Entering directory '/build/harvid/src'
    ld -r -b binary -o seek.o ../doc/seek.js
    ld -r -b binary -o logo.o ../doc/harvid.jpg
    make[1]: *** No rule to make target '../libharvid/libharvid.a', needed by 'harvid'.  Stop.

pkgs/tools/video/harvid/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, ffmpeg, libjpeg, libpng, pkg-config }:
+{ lib, stdenv, fetchFromGitHub, fetchpatch, ffmpeg, libjpeg, libpng, pkg-config }:
 
 stdenv.mkDerivation rec {
   pname = "harvid";
@@ -11,6 +11,16 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-qt6aep7iMF8/lnlT2wLqu6LkFDqzdfsGLZvrOlXttG8=";
   };
 
+  patches = [
+    # Fix pending upstream inclusion to support parallel builds:
+    #   https://github.com/x42/harvid/pull/10
+    (fetchpatch {
+      name = "parallel-build.patch";
+      url = "https://github.com/x42/harvid/commit/a3f85c57ad2559558706d9b22989de36452704d9.patch";
+      sha256 = "sha256-0aBfM/4XEqM7C1nFw996IVwaeL0tNgMUQ1C3kblOobI=";
+    })
+  ];
+
   nativeBuildInputs = [ pkg-config ];
 
   buildInputs = [ ffmpeg libjpeg libpng ];