[gpsd-dev] New fix logic breaks control commands

[Fred Wright]

I've been fiddling with ubxtool some, and noticed a problem.  Scenario:

A u-Blox receiver with no antenna connected.  So no fixes, but 
communication (USB) otherwise works.

If I do "./ubxtool -f <port> -p VER", it works.

If I do "gpsd -n <port>" and then "./ubxtool -p VER", it works.  The 
installed gpsd is 3.18.1

If I do "./gpsd -n <port>" and then "./ubxtool -p VER", it gets no 
response.  This is with the latest gpsd 3.19-dev.

I suspect that the rework related to fixes is keeping messages from 
getting through when there's no fix.  Aside from control messages that 
have nothing to do with fixes, the receiver sometimes sends NAV messages 
even without a fix, and it doesn't make sense to hide them.

I can bisect if needed, but this is probably easily reproducible.

Fred Wright