cmake：指定find_package的搜索路径

find_package(OpenCV
        PATHS /opt/opencv
        NO_DEFAULT_PATH
        REQUIRED)
if (OpenCV_FOUND)
    include_directories(${
    
    OpenCV_INCLUDE_DIRS})
    message( ${
    
    OpenCV_LIBS})
else()
    message("OpenCV not found, so we won't build the project.")
endif()