config.h includes were missing in a few files, including input.c, the
lack of which caused the X11 backend to segfault instantly due to not
having an xkbcommon context.
Signed-off-by: Daniel Stone <daniel@fooishbar.org>
This change spills the code for looking up a seat by name and then
potentially creating it if it doesn't exist into a new function called
udev_seat_get_named.
This change allows us to reuse this code when looking up the seat
when parsing seat constraints per output.
By labelling devices with ENV{WL_SEAT} in udev rules the devices will be
pulled into multiple weston seats.
As a result you can get multiple independent seats under the DRM and
fbdev backends.
And as a result of this stop iterating through the compositor seat list
(of one item) and instead access the udev_input structure directly.
This enables a refactoring to pull out the weston_seat into a separate
structure permitting multiple seats.
We always call enable_udev_monitor and add_devices together and always
disable_udev_monitor and remove_devices together. Let's just have one
entry point for enable and one for disable.
