net/asterisk13: memory leak under 12-CURRENT?

Befor starting a PR I'd liek to ask for some advice to document a supposedly
existent memory leak in net/asterisk13 and 12-CURRENT.

Background:

Running recent 12-CURRENT (FreeBSD 12.0-CURRENT #58 r323999: Tue Sep 26
06:18:27 CEST 2017 amd64) on a PCengine APU 2C4, equipted with 4GB of RAM and
4080 KB free after the most recent SeaBIOS has been started, I try to utilise a
net/asterisk13 as PBX on that platform. Asterisk13 has been build via poudriere
and is compiled with CLANG/LLVM, not GCC!

When FreeBSD (NanoBSD) has been started, depending on the recent revision of the
OS/Kernel, top shows ~3680 - 3705 MBytes of free memory. Starting
net/asterisk13 via "service asterisk onestart" indicates an overall usage of up
to 100 MBytes of memory. After having now run the Asterisk 13.17.2 daemon for
two days resulted in ~ 3100 MBytes of free memory, while the asterisk daemon
was still running and doing nothing. But performing several restarts on a
freshly started box gives the same result after ~ 10 restarts - and even after
stopping asterisk and let the system run for a couple of days doesn't free the
memory. I stopped after 15 restarts or so watching the loss of memory after
each restart of asterisk, so i came to the conclusion that there must be a
memory leak somewhere. now i try to provide more informations as needed for a
PR.

Can someone help?

Thanks in advance,

Oliver