chan_ooh323: fix rtptimeout general value checking

correct condition to check rtptimeout in [general] config section

ASTERISK-24393 #close
Reported by:  Dmitry Melekhov
Tested by:  Dmitry Melekhov
Patches:
  ASTERISK-24393.patch
........

Merged revisions 425547 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@425548 65c4cc65-6c06-0410-ace0-fbb531ad65f3