Attempt at mac fix.

libethash-cl/CMakeLists.txt

@@ -24,7 +24,7 @@ include_directories(${Boost_INCLUDE_DIRS})
 include_directories(..)
 add_library(${EXECUTABLE} ${SRC_LIST} ${HEADERS})
 target_include_directories(${EXECUTABLE} PUBLIC ${OpenCL_INCLUDE_DIR})
-target_link_libraries(${EXECUTABLE} ${OpenCL_LIBRARIES} ethash ${Boost_RANDOM_LIBRARIES})
+target_link_libraries(${EXECUTABLE} ${OpenCL_LIBRARIES} ethash ${Boost_RANDOM_LIBRARIES} ${Boost_SYSTEM_LIBRARIES})
 
 install( TARGETS ${EXECUTABLE} RUNTIME DESTINATION bin ARCHIVE DESTINATION lib LIBRARY DESTINATION lib )
 install( FILES ${HEADERS} DESTINATION include/${EXECUTABLE} )