Make the call to wait_until_system_clock more explicit.

MSVC complains about this:
.\tensorflow/core/platform/default/mutex.h(33): error C2872: 'internal': ambiguous symbol
.\tensorflow/core/platform/default/mutex.h(24): note: could be 'tensorflow::internal'

PiperOrigin-RevId: 289244001
Change-Id: I280cf2a3dbc4c87a38371da53fe20bbae3e06187
diff --git a/tensorflow/core/platform/default/mutex.h b/tensorflow/core/platform/default/mutex.h
index 8009f27..7838657 100644
--- a/tensorflow/core/platform/default/mutex.h
+++ b/tensorflow/core/platform/default/mutex.h
@@ -30,7 +30,7 @@
 template <class Rep, class Period>
 std::cv_status condition_variable::wait_for(
     mutex_lock &lock, std::chrono::duration<Rep, Period> dur) {
-  return internal::wait_until_system_clock(
+  return tensorflow::internal::wait_until_system_clock(
       &this->cv_, &lock.mutex()->mu_, std::chrono::system_clock::now() + dur);
 }