Replace spare in msg 31 with processing_status field.
Replace spare in msg 31 with processing_status field.

Build 14.0 repurposed a spare field to indicate the status of some
signal processing techniques (radial by radial noise and coherency based
thresholding).

Unidata/MetPy,dopplershift/MetPy,jrleeman/MetPy,ahaberlie/MetPy,ahaberlie/MetPy,ahill818/MetPy,jrleeman/MetPy,deeplycloudy/MetPy,dopplershift/MetPy,Unidata/MetPy,ShawnMurd/MetPy