Fix NDK API on old devices.

Change-Id: Ie2b1b57735a79febc0937fcc4b65cddd0eb80c16
diff --git a/cpp/rsCppInternal.h b/cpp/rsCppInternal.h
index 904c5ab..ae43d47 100644
--- a/cpp/rsCppInternal.h
+++ b/cpp/rsCppInternal.h
@@ -17,6 +17,7 @@
 #ifndef ANDROID_RS_CPP_INTERNAL_H
 #define ANDROID_RS_CPP_INTERNAL_H
 
+#define LOG_TAG "rsC++"
 #include "rsCppUtils.h"
 
 #define tryDispatch(rs, dispatch)               \