Fix crash with invalid frame data
The crash was happening as a result of a frame containing an invalid data
pointer, but was set with data length of zero. The few times the issue was
reproduced it _seemed_ that the frame was queued properly, that is the data
pointer was set to NULL. I never could reproduce the crash so as a last resort
the crash has been fixed, but a check in __ast_read has been added to give as
much information about the source of problematic frames in the future.
(closes issue #16058)
Reported by: atis
git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@231911
65c4cc65-6c06-0410-ace0-
fbb531ad65f3