Add status_matchers.h include to buffer_mapping_test.

Fixes #66

PiperOrigin-RevId: 274933258
diff --git a/iree/hal/buffer_mapping_test.cc b/iree/hal/buffer_mapping_test.cc
index 8a3b8a1..1f21b9b 100644
--- a/iree/hal/buffer_mapping_test.cc
+++ b/iree/hal/buffer_mapping_test.cc
@@ -24,6 +24,7 @@
 #include "gtest/gtest.h"
 #include "absl/types/span.h"
 #include "iree/base/status.h"
+#include "iree/base/status_matchers.h"
 #include "iree/hal/buffer.h"
 
 namespace iree {