cmake HAVE_GTK3 examples

SsageParuders/Android_Native_Surface my_android_opencv/modules/highgui/misc/plugins/plugin_gtk/CMakeLists.txt :46 

elseif(HAVE_GTK3)

joachimBurket/esp32-opencv modules/highgui/CMakeLists.txt :124 

elseif(HAVE_GTK OR HAVE_GTK3)

plumonito/dtslam 3rdparty/opencv-git/modules/highgui/CMakeLists.txt :71 

elseif(HAVE_GTK OR HAVE_GTK3)