Renamed MEX define

CMakeLists.txt

@@ -62,7 +62,7 @@ if(WITH_MEX)
 
   SET(MEX_LIBRARIES ${MEX_LIBMX} ${MEX_LIBMEX} ${MEX_LIBMAT})
   SET(MEX_ENDING ".mexa64")
-  ADD_DEFINITIONS("-DNICE_MEX_FOUND")
+  ADD_DEFINITIONS("-DNICE_USELIB_MEX")
   MESSAGE(STATUS "Found mex libraries at ${MEX_LIBRARIES}")
 endif()