Log message:
math/volk: import volk-2.3.0

The Vector-Optimized Library of Kernel is a library that contains kernels of
hand-written SIMD code for different mathematical operations. Since each SIMD
architecture can be very different and no compiler has yet come along to
handle vectorization properly or highly efficiently, VOLK approaches the
problem differently.

VOLK is a sub-project of GNU Radio.