maybe fix mac build

  system/core/libnativebridge/tests/CodeCacheExists_test.cpp:30:15: error:  use of undeclared identifier 'ENOENT'
      ASSERT_EQ(ENOENT, errno);

Change-Id: I188074b878a7ec3955a9f4b5dc7d1bfc56e2ccbc
diff --git a/libnativebridge/tests/CodeCacheCreate_test.cpp b/libnativebridge/tests/CodeCacheCreate_test.cpp
index 6aa8eaa..58270c4 100644
--- a/libnativebridge/tests/CodeCacheCreate_test.cpp
+++ b/libnativebridge/tests/CodeCacheCreate_test.cpp
@@ -16,6 +16,7 @@
 
 #include "NativeBridgeTest.h"
 
+#include <errno.h>
 #include <sys/stat.h>
 #include <unistd.h>