[NaCl SDK] Add nacl_io and sdk_util namespaces.

native_client_sdk/src/libraries/sdk_util/auto_lock.h

Index: native_client_sdk/src/libraries/sdk_util/auto_lock.h
diff --git a/native_client_sdk/src/libraries/sdk_util/auto_lock.h b/native_client_sdk/src/libraries/sdk_util/auto_lock.h
index b60fd8dee195ab969dedd4007a1c811e00854a34..ec8d3cf640d13471af8cb71c9d56bf1eaaa6656f 100644
--- a/native_client_sdk/src/libraries/sdk_util/auto_lock.h
+++ b/native_client_sdk/src/libraries/sdk_util/auto_lock.h
@@ -10,11 +10,12 @@
 #include "sdk_util/macros.h"
 #include "sdk_util/simple_lock.h"
 
+namespace sdk_util {
 
 // This macro is provided to allow us to quickly instrument locking for
 // debugging purposes.
 #define AUTO_LOCK(lock)                         \
-  AutoLock Lock##__LINE__(lock);
+  ::sdk_util::AutoLock Lock##__LINE__(lock);
 
 class AutoLock {
  public:
@@ -38,5 +39,7 @@ class AutoLock {
   DISALLOW_COPY_AND_ASSIGN(AutoLock);
 };
 
+}  // namespace sdk_util
+
 #endif  // LIBRARIES_SDK_UTIL_AUTO_LOCK_H_