Allow better busy detect debugging (with BUSYDETECT_DEBUG).

Remove very old BUSYDETECT and BUSY_DETECT_MARTIN defines.

(closes issue #11107)
Patches:
      busydetect_enhancement.patch uploaded by agx (license 298)
      busydetect-r94975.diff uploaded by sergee (license 138)

Additional changes/cleanup by me.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@98998 65c4cc65-6c06-0410-ace0-fbb531ad65f3