Crash when using G.729 codec

```
What steps will reproduce the problem?
1. Build doubango using the attached patch to enable G.729 and enable debug.
2. Copy generated libs from android-projects/output/gpl/imsdroid/libs in
android-ngn-stack
3. Place a call between two smartphones running the generated version of
Imsdroid using G.729 codec

What is the expected output? What do you see instead?
The call should stay up until one of the two parties hangs. The call, instead,
is interrupted after a while (varing from seconds/minutes to hours) due to a
crash of doubango on one of the parties.

What version of the product are you using? On what operating system?
Doubango r1233 / android-ngn-stack and imsdroid r579.
Reproduced on the following devices:
- Nexus 5/Android 5.0.1
- GT-I9505/Android 4.4.2
- SM-G900F/Android 4.4.2
- GT-I9100/Android 4.1.2

Please provide any additional information below.
Please find attached logcat and wireshark traces on a crash happened after few
seconds on the GT-I9505 running Android 4.4.2.

Unfortunately, even enabling the debug (each version of tinyWRAP lib exceeds
80MB), we don't get detailed info about the crash reason, just a line stated
"Process org.doubango.imsdroid (pid 15298) (adj 0) has died".

```

Original issue reported on code.google.com by `massimo....@gmail.com` on 16 Feb 2015 at 9:09

Attachments:
- [doubango.enable.g729.patch](https://storage.googleapis.com/google-code-attachments/imsdroid/issue-546/comment-0/doubango.enable.g729.patch)
- [imsdroid.579-doubango.1233-g729.gti9505.txt](https://storage.googleapis.com/google-code-attachments/imsdroid/issue-546/comment-0/imsdroid.579-doubango.1233-g729.gti9505.txt)
- [imsdroid.579-doubango.1233-g729.gti9505.pcap](https://storage.googleapis.com/google-code-attachments/imsdroid/issue-546/comment-0/imsdroid.579-doubango.1233-g729.gti9505.pcap)

Start by reproducing the call using the attached doubango.enable.g729.patch and the generated libraries under android-projects/output/gpl/imsdroid/libs. Examine the attached logcat and Wireshark trace for the crash, then verify that a G.729 call remains active instead of terminating the Android process on the listed devices.

Written by the indexing model from the issue text.