UI: Remove x11info dependency

This moves X11 platform to the qt private functions, as x11info was
removed from Qt6 so this is required for a clean Qt5/6 transition.

This is the implementation of x11info::getdisplay so it should still
work on older platforms. This "API" doesnt really guarantee anything
though.

Also clean up wayland only bits as we use them for all windowing systems
now, and the name of the native pointer we want is the same on both
platforms for now.

UI/CMakeLists.txt

@@ -123,13 +123,17 @@ elseif(APPLE)
 	endif()
 
 elseif(UNIX)
-        find_package(Qt5X11Extras REQUIRED)
+	find_package(Qt5Gui REQUIRED)
+
+	include_directories(${Qt5Gui_PRIVATE_INCLUDE_DIRS})
 
 	set(obs_PLATFORM_SOURCES
 		platform-x11.cpp)
 
-        set(obs_PLATFORM_LIBRARIES
-                Qt5::X11Extras)
+	set(obs_PLATFORM_LIBRARIES
+		${obs_PLATFORM_LIBRARIES}
+		Qt5::Gui
+		Qt5::GuiPrivate)
 
 	if("${CMAKE_SYSTEM_NAME}" MATCHES "FreeBSD")
 		list(APPEND obs_PLATFORM_LIBRARIES
@@ -396,16 +400,6 @@ if(WIN32)
 			OUTPUT_NAME "obs${_output_suffix}")
 endif()
 
-if (ENABLE_WAYLAND)
-	find_package(Qt5Gui REQUIRED)
-	include_directories(${Qt5Gui_PRIVATE_INCLUDE_DIRS})
-
-	set(obs_PLATFORM_LIBRARIES
-		${obs_PLATFORM_LIBRARIES}
-		Qt5::Gui
-		Qt5::GuiPrivate)
-endif()
-
 target_link_libraries(obs
 	libobs
 	Qt5::Widgets