Update CMakeLists.txt

Remove empty option.

CMakeLists.txt

@@ -256,7 +256,6 @@ IF ((CMAKE_C_COMPILER_ID MATCHES "GNU") AND NOT CMAKE_COMPILER_IS_MINGW)
 ELSEIF(MSVC)
   # enable multi-core compilation with MSVC
   ADD_COMPILE_OPTIONS(/MP /bigobj /W4 /WX ) 
-  ADD_COMPILE_OPTIONS(  )
   # disable "elements of array '' will be default initialized" warning on MSVC2013
   IF(MSVC12)
     ADD_COMPILE_OPTIONS(/wd4351)