Fix cmake error related to difference of CMake generators in OpenCV build (#197)

Author: aobolensk

cmake/opencv_config.cmake

@@ -5,6 +5,7 @@ execute_process(
     COMMAND ${CMAKE_COMMAND} 
         -S "${CMAKE_SOURCE_DIR}/3rdparty/opencv" 
         -B "${OPENCV_BUILD_DIR}" 
+        -G "${CMAKE_GENERATOR}"
         -DCMAKE_C_COMPILER_LAUNCHER=${CMAKE_C_COMPILER_LAUNCHER} 
         -DCMAKE_CXX_COMPILER_LAUNCHER=${CMAKE_CXX_COMPILER_LAUNCHER} 
         -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}