Previously, NUM_COPY was used in ssdp_device.c to send multiple copies
of each advertisements but also multiple replies to each M-SEARCH
request. As sending multiple replies is not compliant with HTTPU/MU
spec, NUM_COPY has been set to 1 in an older patch. However, as this
variable is not needed and has been replaced with SSDP_COPY, it has
been removed.
(cherry picked from commit 2d22e997e1ff06ad2b202623d73f4d3f321c6131)
56e0fdd438