[DEBUG](Android) Fix large BLEFTP reads.
[DEBUG](Android) Fix large BLEFTP reads.

- Fix a bug which could cause the BLEFTP to crash when reading large
  packets.
- Use a more generous buffer allocation algorithm to prevent
  reallocating for each received block.
- Add a few comments.

149393437/ARSDKBuildUtils,niavok/ARSDKBuildUtils,cvramire/ARSDKBuildUtils,cvramire/ARSDKBuildUtils,aoi/ARSDKBuildUtils,pwkalana9/ARSDKBuildUtils,Parrot-Developers/ARSDKBuildUtils,pwkalana9/ARSDKBuildUtils,niavok/ARSDKBuildUtils,Parrot-Developers/ARSDKBuildUtils,149393437/ARSDKBuildUtils,aoi/ARSDKBuildUtils