This modem is a special case. It uses a given socket ID value rather
than providing one. A naive solution here would be to directly map the
index of a CellularSocket object in the CellularSocket container. But
considering the case where there are multiple sockets being opened (some
sockets being already created at the modem and some yet not created), direct mapping
to indices will not work. As it can happen that the CellularSocket
object is allocated but the socket id is not assigned yet as it is not
actually created on the modem.
In such a case, we check the container and assign the socket id from the
pool if an empty slot was found.
Fix the following warning seen when built with GCC_ARM with mbed-cli v1.8.3
$ mbed compile -c -t GCC_ARM -m K64F
<snip>
[Warning] QUECTEL_M26_CellularStack.cpp@364,9: variable 'sent_acked' set but not used [-Wunused-but-set-variable]
<snip>
Martin Kojtal
Mirela Chirica
Hasnain Virk
Teppo Järvelin
mudassar-ublox
Ari Parkkila
Naveen Kaje
Terence Zhang