Trim down the Windows build a bit

Remove most unused Adwaita icons and cursors, it's about 30 mebibytes
of raw bullshit that doesn't seem to be missing in any shape or form.

Rather sadly, the script is too complex to be rewritten in CMake script.

CMakeLists.txt

@@ -264,6 +264,9 @@ elseif (WITH_GUI)
 		DESTINATION share/icons/hicolor)
 
 	install (SCRIPT cmake/Win32Cleanup.cmake)
+	install (CODE "execute_process (COMMAND
+		sh \"${PROJECT_SOURCE_DIR}/cmake/Win32CleanupAdwaita.sh\"
+		WORKING_DIRECTORY \${CMAKE_INSTALL_PREFIX})")
 endif ()
 
 # Do some unit tests