skia: make use of gnFlags

pkgs/by-name/sk/skia/package.nix

@@ -70,16 +70,14 @@ stdenv.mkDerivation (finalAttrs: {
     vulkan-memory-allocator
   ];
 
-  configurePhase = let
+  gnFlags = let
     cpu = {
       "x86_64" = "x64";
       "i686" = "x86";
       "arm" = "arm";
       "aarch64" = "arm64";
     }.${stdenv.hostPlatform.parsed.cpu.name};
-  in ''
-    runHook preConfigure
-    gn gen build --args='${toString ([
+  in [
     # Build in release mode
     "is_official_build=true"
     "is_component_build=true"
@@ -99,10 +97,7 @@ stdenv.mkDerivation (finalAttrs: {
     "libwebp"
   ] ++ lib.optionals enableVulkan [
     "skia_use_vulkan=true"
-    ])}'
-    cd build
-    runHook postConfigure
-  '';
+  ];
 
   # Somewhat arbitrary, but similar to what other distros are doing
   installPhase = ''
@@ -113,10 +108,10 @@ stdenv.mkDerivation (finalAttrs: {
     cp *.so *.a $out/lib
 
     # Includes
-    pushd ../include
+    pushd ../../include
     find . -name '*.h' -exec install -Dm644 {} $out/include/skia/{} \;
     popd
-    pushd ../modules
+    pushd ../../modules
     find . -name '*.h' -exec install -Dm644 {} $out/include/skia/modules/{} \;
     popd