The libsonic.so files in the armeabi and armeabi-v7a folders are built from the sonic-ndk project, located here:
https://github.com/waywardgeek/sonic-ndk

For convenience to anybody else who wishes to build my code, I'm placing only the built library so you don't need to use the NDK.
Since the library contains files licensed under the LGPL, you can read the license in the COPYING file.

Note that the LGPL ONLY applies the Sonic libraries under this directory and not to any of the other Prestissimo sources.