add speex 16khz sample frame so codec cost can be calculated

(closes issue #17534)
Reported by: fabled
Patches:
      speex-wb-sample.diff uploaded by fabled (license 448)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@271625 65c4cc65-6c06-0410-ace0-fbb531ad65f3