No GL support on Fuchsia.

Change-Id: Ibd5bd82c9967b6fd10fcf2269db60b6af3d55cbb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/253257
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

Author: rosasco-wk

BUILD.gn

@@ -500,7 +500,11 @@ optional("gpu") {
   if (skia_generate_workarounds) {
     deps += [ ":workaround_list" ]
   }
-  public_defines = [ "SK_GL" ]
+  if (!is_fuchsia) {
+    public_defines = [ "SK_GL", ]
+  } else {
+    public_defines = []
+  }
   public_configs = []
   public_deps = []