The "restrict" keyword can be used to indicate that no other
pointer will be used to access a chunk of memory while the
restricted pointer is alive. If that promise is not upheld,
undefined behavior is triggered.
It may be difficult to ensure this property, and the property may
be brittle - becoming invalid as code evolves. Just like "inline",
let's just leave optimizations up to the compiler to figure out.
libseat provides all session functionality, so there is no longer need
for a session backend abstraction. The libseat device ID, seat handle
and event loop handle are moved to the main wlr_session and wlr_device
structs.
