The channel needs to stay locked while running timer callbacks, as they access

The channel needs to stay locked while running timer callbacks, as they access
and modify channel data that may change elsewhere.  I went through every timer
callback in the source tree to make sure that none of them did any additional
locking that could introduce deadlocks, and all is well.

(closes issue #10765)
Reported by: Ivan
Patches:
      ast_1_4_11_svn_patch_channel_rc.diff uploaded by Ivan (license 229)

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@86330 65c4cc65-6c06-0410-ace0-fbb531ad65f3