libstagefright: poke the udp hole twice for future incoming udp packets

- only firing off udp packets once to the source address or the endpoint
  could still be limited in some NAT network environment. As a result,
  client can't receive rtp packets over udp.

- send udp packets to both of the two addresses if they are available.

Change-Id: I7e8a0b36a82bcd85b307c9c15dcfee2bcd7e6030
rtsp: keep some damaged access unit to enhance fault tolerance

Make RTSPSource to accept some damaged access units of H263 to enhance
fault tolerance. Without this patch, damaged access can cause failure of
playback.

Change-Id: I905648f8b30fefa6ec8de18f943ede87641d7300
CRs-Fixed: 687252