Our default build probably shouldn't include non-free software.  With
mod_ilbc, the licensing situation is merely ambiguous.  With
mod_siren, the user can't use this code without getting explicit
permission from Polycom (though it is apparently easily given).

The test was backward.  If the revision is in switch_version.h.in then
we have the version already.

These codecs are non-free which creates issues for distributions, so
let's not require these by default to run our example configs.  We can
add back in iLBC once we resolve the licensing situation with our
in-tree implementation.

We believe it to be safe now.  In test run on multi-core machines it
is producing bit-for-bit identical result compared to the non-parallel
invocation.

build_all call each of these subroutines under a sub-shell, so the set
-e gets wiped out.

Because we're capturing the string return value of these functions, we
can't see any output that goes to stdout.

We've moved the sounds to a separate source package.

Add some attributes that are useful for packaging.

install-build-depends is inferior to:

  mk-build-deps -i

Reference-URL: http://jira.freeswitch.org/browse/FS-4260Tested-by: Stefan Knoblich <stkn@openisdn.net>
Signed-off-by: Stefan Knoblich <stkn@openisdn.net>

We often tell people to enable this for various reasons; it likely
makes a sensible default.

I've changed the variable name from cc_export to cc_export_vars to be more consistant from the original patch

git-pull learned about pull.rebase in git-1.7.9.  This value is used
as a fallback if branch.<name>.rebase isn't found.