Simplify the thunk targets since we don't support apps as components

mojo/public/gles2/BUILD.gn

-# Copyright 2014 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-# In an is_component_build build, everything can link against //mojo/gles2
-# because it is built as a shared library. However, in a static build,
-# //mojo/gles2 is linked into an executable (e.g., mojo_shell), and must be
-# injected into other shared libraries (i.e., Mojo Apps) that need the mojo
-# gles2 API.
-#
-# For component targets, add //mojo/public/gles2:for_component to your deps
-# section.
-#
-# For shared_library targets (e.g., a Mojo App), add
-# //mojo/public/gles2:for_shared_library to your deps
-
-group("for_shared_library") {
-  public_configs = [ "//third_party/khronos:khronos_headers" ]
-  public_deps = [ "//mojo/public/c/gles2" ]
-
-  if (is_component_build) {
-    deps = [ "//mojo/gles2" ]
-  } else {
-    deps = [ "//mojo/public/platform/native:gles2_thunks" ]
-  }
-}
-
-group("for_component") {
-  public_configs = [ "//third_party/khronos:khronos_headers" ]
-  public_deps = [ "//mojo/public/c/gles2" ]
-
-  if (is_component_build) {
-    deps = [ "//mojo/gles2" ]
-  }
-}