shm/shm: use "this" in operator<
shm/shm: use "this" in operator<

Ordering of struct Page and its data pointer is the same.  This
eliminates two dereferences.

CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy