sed on Mac is apparently incredibly broken and incapable of adding
newlines.  `printf 'x' | sed 's/x/\n/'` results in 'n' on Mac rather
than a newline.  GNU sed even in --posix mode does not agree with this
behavior.  None the less, we can work around it here.

the callbacks.

SIP-686 changed mod_say (en) to speak full dates when asked to speak a date in the future (rather than only weekday and time).

Some systems don't have the pkg-config file, or don't have it in the
right place.  Breaking build on those systems does have the positive
effect of getting people to file bugs with those distros, but we
should at least keep things working on Debian wheezy while getting
Debian to accept the fix to ldns.

FS-353: look for ldns pkg-config for homebrew, you will need to update your homebrew ldns package if you installed it prior to this commit, they just fixed the pkg-config file being installed

POSIX says poll.h and signal.h should not be prefixed with sys/ (ie
poll.h instead of sys/poll.h)

limits.h also defines a TZNAME_MAX so we change name of the define for
spandsp.

When we couldn't acquire the rwlock on the conference we were leaking
a buffer we just allocated.  On a 48k/10ms conference we would leak
960 bytes per attempt.

FS-6500: freetdm: Add more enum compliance by defining proper enum values for FTDM_END and FTDM_ANY special state values

This library is used only by mod_enum and is available on most
platforms.  The version in our tree has many code quality problems
that are generating noise when doing static analysis.  Suffice it to
say we want rid of it as our responsibility.

FS-353