Add nacl_sdk gyp meta-target.

src/untrusted/valgrind/valgrind.gyp

+# Copyright (c) 2012 The Native Client Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'includes': [
+    '../../../build/common.gypi',
+  ],
+  'conditions': [
+    ['target_arch!="arm"', {
+      'targets' : [
+        {
+          'target_name': 'valgrind_lib',
+          'type': 'none',
+          'variables': {
+            'nlib_target': 'libvalgrind.a',
+            'nso_target': 'libvalgrind.so',
+            'build_glibc': 1,
+            'build_newlib': 1,
+          },
+          'sources': [
+            'valgrind_interceptors.c',
+          ],
+        },
+        {
+          'target_name': 'dynamic_annotations_lib',
+          'type': 'none',
+          'variables': {
+            'nlib_target': 'libdynamic_annotations.a',
+            'nso_target': 'libdynamic_annotations.so',
+            'build_glibc': 1,
+            'build_newlib': 0,
+          },
+          'sources': [
+            'dynamic_annotations.c',
+          ],
+        }
+      ],
+    }],
+  ],
+}