SQLite Android NDK add custom functions

I have managed to get SQLite setup using the NDK but I can't managed to get custom functions to work which was the whole reason for implementing SQLite using the NDK.

I used this library to get the same SQLite files. It also contains an extension file called extensionfunctions.c which adds in string and mathematical functions for SQLite.

From what I can see the SQLite implementation appears to be working correctly but I cannot call any of the custom functions.

I've little to no knowledge of C/C++ so any help would be great. Do I have to compile the extensionfunctions.c file independently and then add in the so file with the libsqliteX.so file? Or do I have to make a call in the android_database_SQLiteCommon.cpp to load in the other extension? I've no idea how this works.