glslviewer: fix darwin build

pkgs/development/tools/glslviewer/default.nix

···
-{ stdenv, fetchFromGitHub, glfw, pkgconfig, libXrandr, libXdamage,
-  libXext, libXrender, libXinerama, libXcursor, libXxf86vm, libXi,
-  libX11, mesa_glu }:
+{ stdenv, fetchFromGitHub, glfw, pkgconfig, libXrandr, libXdamage
+, libXext, libXrender, libXinerama, libXcursor, libXxf86vm, libXi
+, libX11, mesa_glu, Cocoa
+}:
 
 stdenv.mkDerivation rec {
   name = "glslviewer-${version}";
···
 
   # Makefile has /usr/local/bin hard-coded for 'make install'
   preConfigure = ''
-    sed s,/usr/local,$out, -i Makefile
+    substituteInPlace Makefile \
+        --replace '/usr/local' "$out" \
+        --replace '/usr/bin/clang++' 'clang++'
   '';
 
   preInstall = ''
     mkdir -p $out/bin
   '';
-  
-  buildInputs = [ glfw mesa_glu pkgconfig glfw libXrandr libXdamage
-                  libXext libXrender libXinerama libXcursor libXxf86vm
-                  libXi libX11 ];
-  
+
+  buildInputs = [
+    glfw mesa_glu pkgconfig glfw libXrandr libXdamage
+    libXext libXrender libXinerama libXcursor libXxf86vm
+    libXi libX11
+  ] ++ stdenv.lib.optional stdenv.isDarwin Cocoa;
+
   meta = with stdenv.lib; {
     description = "Live GLSL coding renderer";
     homepage = http://patriciogonzalezvivo.com/2015/glslViewer/;

pkgs/top-level/all-packages.nix

···
 
   glock = callPackage ../development/tools/glock { };
 
-  glslviewer = callPackage ../development/tools/glslviewer { };
+  glslviewer = callPackage ../development/tools/glslviewer {
+    inherit (darwin.apple_sdk.frameworks) Cocoa;
+  };
 
   gmic = callPackage ../tools/graphics/gmic { };