Make drag-and-drop work on FreeBSD
Currently drag-and-drop doesn't work on FreeBSD because relevant input parts of kwayland-server are not compiled there.
HAVE_LINUX_INPUT_H is set to 0 on FreeBSD because linux/input.h is in /usr/local/include and check_include_file() doesn't look there.
Regardless of that, as FreeBSD developers pointed out, including linux/input.h is the recommended way to get input event codes so let's make it a hard dependency.
This should fix testDataDevice on FreeBSD.
Edited by Vlad Zahorodnii