The ad9361 util.c includes a function __ffs() which returns the first LSB bit that is set using a 0-base notation.
This function mirrors the BSD function ffs() and the GLIB 2.0 implementation with the symbol __ffs() which returns the first LSB bit that is set using a 1-base notation.
If you end up linking the wrong library, certain code will not work. (Ask me how I know...)
Recommand ADI not use a Linux standard function name for different behavior.