Pass LDFLAGS to linking step
Use a pattern-specific dir variable so we can use it in the rule definitions
Remove unused udev field in struct swc

This is now contained in seat.c if ENABLE_HOTPLUGGING is set.
compositor: Remove redundant setting of x and y in handle_motion
Add optional support for libinput

Fixes #5.
Remove obsolete libswc-shared target
data{,_device{,_manager}}: Drop swc_ prefix for non-public structures/functions
Add missing call to data_device_finalize() in seat_finalize()