misc trace format string fixes

[ourairquality]

No description provided.

[rtklibexplorer]

From AI review:

1. src/rcv/unicore.c: sysno is undeclared — won't compile. The local int satsys (which shadows the global satsys() function) was already correct as %d/satsys in the original; looks like a rename was started but only applied to the trace() call, not the declaration or the switch.
2. app/qtapp/rtkplot_qt/plotmain.cpp, mouseReleaseEvent's #else (pre-Qt6) branch: changed to %f, but event->globalPos() returns QPoint, whose .x()/.y() are int — this introduces a mismatch that wasn't there before. The #if (Qt6) branch above it is correct since globalPosition() returns QPointF.

[ourairquality]

Good points, fixed.