gpu/khronos_glcts_support: Move target_defaults into separate file

gpu/khronos_glcts_support/khronos_glcts_defaults.gypi

+# Copyright 2015 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.
+
+{
+  'target_defaults': {
+    'defines': [
+      'DEQP_TARGET_NAME="chrome-gpu-command-buffer"',
+      'DEQP_SUPPORT_GLES2=1',
+      'DEQP_SUPPORT_EGL=1',
+      'GTF_API=GTF_GLES20',
+    ],
+    'conditions': [
+      ['OS=="linux"', {
+        'defines': [
+          '_XOPEN_SOURCE=500',
+        ],
+        'cflags!': [
+          '-fno-exceptions',
+        ],
+        'cflags_cc!': [
+          '-fno-exceptions',
+        ],
+        'target_conditions': [
+          ['_type=="static_library"', {
+            'cflags_cc!': [
+              '-fno-rtti',
+            ],
+          }],
+        ],
+      }],
+    ],
+  },
+}