Update configure script to check for Zaptel VLDTMF support since this will now...

Update configure script to check for Zaptel VLDTMF support since this will now be required. If you build and don't have Zap stuff, upgrade your zaptel copy. As well - change some minor things so that we get "checking for" and not "checking checking for".


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@41505 65c4cc65-6c06-0410-ace0-fbb531ad65f3