Prevent inf when presented with 0 errormax

acos(1) returns 0, so this implies infinite segements to get to 0 error.
This is not reasonable but might be encountered in bad arcs or circles
that have 0 radius.  Instead of returning infinite or std::max segments,
we limit the error to be at least 1 IU

libs/kimath/src/geometry/geometry_utils.cpp

@@ -46,6 +46,7 @@ int GetArcToSegmentCount( int aRadius, int aErrorMax, const EDA_ANGLE& aArcAngle
 
     // avoid divide-by-zero
     aRadius = std::max( 1, aRadius );
+    aErrorMax = std::max( 1, aErrorMax );
 
     // error relative to the radius value:
     double rel_error = (double)aErrorMax / aRadius;