During development multiple ModemAdded callbacks were seen,
which caused duplicate modems to be created. Since then this
condition has never been seen again, so instead of exiting
we will just print and return. This wont allow duplicate modems
to be created anyways so its much better to do this than fataly
exiting.
GLIBC is not necessarily the only library that provides execinfo.
With libexecinfo execinfo can be used also in other Libraries.
The patch lets the configure check the existence of the header
and the libexecinfo Library and uses them if avaible.
(also fixes compilation if execinfo is not avaible)
Implements a sim auth driver that communicates with ofono to handle
GSM/UMTS authentication algorithms. This plugin takes care of
disovering ofono, the modem, IMSI, and SIM capabilities i.e. what
algorithms are supported.
