Make *_unserialize safe to use on buffers in-place
Make *_unserialize safe to use on buffers in-place

By calling memmove instead of memcpy, and walking the buffer backward
from the end, *_unserialize is safe to use in-place.

Signed-off-by: Peter Harris <859d2524afe9d1b926cf5c02089ad1cbab640cc0@opentext.com>

stapelberg/libxcb,stapelberg/libxcb,stapelberg/libxcb