don't segfault after starting sofia, upon xml_open_config lookup failure for the profile from launch_sofia_worker_thread

There are a lot of codecs these days, and some clients offer all of
them.  If we run out of space in this buffer our local SDP will get
silently truncated, which will cause a difficult to diagnose error in
Sofia-SIP.

Thanks to Anthony Minessale.

FS-4293 --resolve

This error was causing us to call generate_m with a buffer length that
was less than the strlen of the buffer we were passing.  The result
was truncated local SDP which would cause sofia to fail if the
truncation was in a particularly bad place.

Thanks to Anthony Minessale for the fix and working with me to
diagnose the issue.

FS-4293 --resolve

This amends commit a6bb4545.

Related to issue FS-4293.

 * fixed bug with remote hello-hash buffer being too small
 * removed unused hello-hash storage in zrtp stream context
 * fixed bug with libzrtp rendered "empty" SAS hash from incoming
   SasRelay packet
 * incremented libzrtp version number to 1.15
Signed-off-by: Travis Cross <tc@traviscross.com>

It's broken too many of my recent builds.  We can add it back in when
things stabilize or perhaps after we get it to swig with a recent
version of swig that we can make part of the clean bootstrap/build
process.

POSIX sed doesn't support grouping, so split the regex in two.

Reference-URL: http://jira.freeswitch.org/browse/FS-4276Signed-off-by: Stefan Knoblich <stkn@openisdn.net>