libtool: add meta.platforms and make cctools Darwin only

Signed-off-by: Ana Hobden <operator@hoverbear.org>

pkgs/development/compilers/shaderc/default.nix

@@ -42,7 +42,7 @@ in stdenv.mkDerivation rec {
     ln -s ${spirv-headers} third_party/spirv-tools/external/spirv-headers
   '';
 
-  nativeBuildInputs = [ cmake darwin.cctools python3 ];
+  nativeBuildInputs = [ cmake python3 ] ++ lib.optionals stdenv.isDarwin [ darwin.cctools ];
 
   postInstall = ''
     moveToOutput "lib/*.a" $static
@@ -53,6 +53,7 @@ in stdenv.mkDerivation rec {
   meta = with lib; {
     inherit (src.meta) homepage;
     description = "A collection of tools, libraries and tests for shader compilation";
+    platforms = platforms.all;
     license = [ licenses.asl20 ];
   };
 }