replay: use spice_malloc(0) instead of raw malloc
replay: use spice_malloc(0) instead of raw malloc

These function report memory allocation errors.
spice_malloc0 also reset memory after allocation.

Signed-off-by: Frediano Ziglio <55d48b080b2e443e395cde84d2c83b135a4ff48e@redhat.com>
Acked-by: Victor Toso <39b7599ff73bbf5db531748ba5250f21fa7120ff@redhat.com>

SPICE/spice,fgouget/spice,fgouget/spice,SPICE/spice,fgouget/spice,fgouget/spice,SPICE/spice