Fix a bug in RTCP packet processing which caused heap corrupted by overwriting
There were some errors in processing a compound RTCP packet which contains more than one RTCP type. This caused Asterisk crash when receiving some compound RTCP packets because the heap was corrupted by overwritting the dynamically allocated buffer.
Also with the following changes.
- Define AST_BUILDOPT_SUM as "" to avoid loading error: Module 'chan_voicemngr.so' was not compiled with the same compile-time options as this version of Asterisk.
- Update module description in AST_MODULE_INFO()
- Some coding style improvements