Fix crash caused by opaquification change -r356042.

The set_format() function was more subtle in how it modified the
struct ast_channel readtrans/writetrans values.

* Fixed ast_activate_generator() conversion correctly.

(closes issue ASTERISK-19434)
Reported by: Birger Harzenetter
Tested by: rmudgett


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@358861 65c4cc65-6c06-0410-ace0-fbb531ad65f3