HPCC-20694 Add missing include directory to cmake file

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>

testing/unittests/CMakeLists.txt

@@ -47,7 +47,8 @@ include_directories (
          ./../../common/deftype
          ./../../system/security/cryptohelper
          ./../../configuration/config2
-        ${CMAKE_BINARY_DIR}
+         ${CMAKE_BINARY_DIR}
+         ${CMAKE_BINARY_DIR}/oss
     )
 
 ADD_DEFINITIONS( -D_CONSOLE )