[Asterisk-video] fixed AMR in h324m_gw

[Klaus Darilion]

Hi!

I've just commited (a simple) fix (rev 139) for AMR conversion from if2 
to RTP format. Now, h324m_gw works fine with mp4_save and pm4_play.

Nevertheless, if the recorded .3gp file is played with VLC I have video 
but no audio. If the file is played with Quicktime I have audio but now 
video - thus there still may be some problems.

regards
klaus