Revert "Disable GPU support by default when building for host in Fuchsia"

This reverts commit 3e9e6cfc82.

Reason for revert: Causes linker errors when building Fuchsia (Flutter still pulling in Ganesh code).

Original change's description:
> Disable GPU support by default when building for host in Fuchsia
> 
> When building Skia for host as part of Fuchsia build, we don't need
> the GPU support which introduces additional dependency on X11.
> 
> Change-Id: I29a1a8a4b349c1c7d2e7db5c5c44a4cc8917cbdc
> Reviewed-on: https://skia-review.googlesource.com/117381
> Reviewed-by: Mike Klein <mtklein@google.com>
> Commit-Queue: Mike Klein <mtklein@google.com>

TBR=mtklein@google.com,brianosman@google.com,phosek@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: I74755f68653fe217d8691dea939e44f359fc3d8a
Reviewed-on: https://skia-review.googlesource.com/117880
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

BUILD.gn

@@ -37,7 +37,7 @@ declare_args() {
   skia_enable_effects = true
   skia_enable_flutter_defines = false
   skia_enable_fontmgr_empty = false
-  skia_enable_gpu = is_fuchsia || target_os != "fuchsia"
+  skia_enable_gpu = true
   skia_enable_pdf = true
   skia_enable_spirv_validation = is_skia_dev_build && is_debug
   skia_enable_tools = is_skia_dev_build
@@ -1693,7 +1693,7 @@ if (skia_enable_tools) {
     deps = [
       ":flags",
       ":skia",
-      ":tool_utils",
+      ":tool_utils"
     ]
   }