Hi,
VOXL comes with FastCV installed, the 2 headers can be found in /usr/include/fastcv/ and the libs are in /usr/lib/ :
voxl:/$ find /usr | grep fastcv /usr/include/fastcv /usr/include/fastcv/fastcv.h /usr/include/fastcv/fastcvExt.h /usr/lib/libfastcvadsp_stub.so /usr/lib/libfastcvopt.so /usr/lib/rfsa/adsp/libfastcvadsp.so /usr/lib/rfsa/adsp/libfastcvadsp_skel.so