Fix bug with 'F' option for ReceiveFAX and SendFAX.

Skipping the call to set_t38_fax_caps() caused the FAX session
details to not be marked as supporting audio FAX either... the
function's name is a bit misleading. This patch restores the
single bit of non-T.38 behavior from that function when audio
mode is forced.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@304599 65c4cc65-6c06-0410-ace0-fbb531ad65f3