The clamp(v,a,b) function wraps v around the interval [a,b).

However prior to this commit, `clamp` was ignoring the third argument
and using the second argument again in its place.  This resulted in a
division by zero.  Hence `clamp` didn't work at all.

Even if the arguments were treated correctly, `clamp` incorrectly
multiplied rather than added whenever v < a.  This would have produced
bogus results.  (Thanks to Shona McNeill for pointing this out.)

Note that as implemented, `clamp` is undefined for b >= a.

These errors are present in the last upstream C version, v2.7.
They've been corrected in the C++ version that upstream now maintains
instead.

Thanks-to: Shona McNeill <prufrax@googlemail.com>

FS-7070 #resolve

With this commit we allow getting `make -jN` behavior by setting
`parallel=N` in `DEB_BUILD_OPTIONS`.  Setting `parallel=` will result
in `make -j` being run (i.e. no limit on the number of jobs).  The
default is to run one job at a time; this is still the safest bet when
building all modules.

Thanks to Peter Wu for suggesting a different way to do this.

ref: https://www.debian.org/doc/debian-policy/ch-source.html#s-debianrules-options

The lsb-release package isn't a stated dependency and isn't present on
a minimal Debian install.

* commit '0822f6a0':
  FS-7019 swap debian/ubuntu autodetection order
  FS-7019 detect debian explicitly, error on unknown distribution
  FS-7019 add note on how to build on Ubuntu
  FS-7019 full list of distributions to target based on distribution autodetection
  FS-7019 build error on utopic (lber_types.h: No such file or directory)
  FS-7019 add support for building on ubuntu trusty and utopic

* commit '83acda04':
  file_string write failover FS-4930

FS-7083 #resolve #comment this should do it.  The problem is linked to side-effects from the read thread being delayed by writing to the file handle.  It was so much worse on mp3 because the shout encoder blocks while its churning the data and delays it more.  This patch adds a dedicated thread for writing to the file and the channel_variable RECORD_USE_THREAD=false will disable it and sync may still be maintained at the cost of dropping more data from the audio signal.

* commit 'c96d64e7':
  invalid type cast correction
  list_users tipo correction

Merge pull request #143 in FS/freeswitch from bugfix/FS-7095-freeswitch-sends-dtls-hello-and-stun to master

* commit 'ba016c28':
  FS-7095 #comment please test

FS-7083 #comment patch to change mod_shout to use lame_encode_buffer_interleaved on stereo channels so we don't have to mess with the input data

FS-7091 #resolve #comment [mod_rayo] Removed unnecessary mutex lock inside input component's cleanup function since the input component won't be cleaned up unless all references have been released.  This fixes a deadlock when output component is created at the same time an input component completes.

The following values can be read from the event:

sync_lost_percent - Error percentage within the analysis window
sync_lost_count - How many times sync has been lost
cng_count - Counter of confort noise packets
err_samples - Number of samples that did not match the sequence

* Use memmem() and memcmp() for pattern checks
* Use a static pre-built buffer for the write frame