GN: Fuchsia probably cannot link without this.

We removed this _none variant globally, thinking we'd put back platform
specific versions as we added support for those platforms.

We don't have anything for Fuchsia.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2271273002

Review-Url: https://codereview.chromium.org/2271273002

BUILD.gn

@@ -428,7 +428,10 @@ component("skia") {
   }
 
   if (is_fuchsia) {
-    sources += [ "src/ports/SkFontMgr_empty_factory.cpp" ]
+    sources += [
+      "src/gpu/gl/GrGLCreateNativeInterface_none.cpp",
+      "src/ports/SkFontMgr_empty_factory.cpp",
+    ]
   }
 }