Correct the formula for error

The radius should always be positive but simply reversing the sign of
the inner expression only works in some cases

libs/kimath/src/geometry/geometry_utils.cpp

@@ -76,7 +76,7 @@ int CircleToEndSegmentDeltaRadius( int aRadius, int aSegCount )
 
     // aRadius is the radius of the circle tangent to the middle of each segment
     // and aRadius/cos(aplha) is the radius of the circle defined by seg ends
-    int delta = KiROUND( aRadius * ( 1/cos(alpha) - 1 ) );
+    int delta = KiROUND( std::abs( aRadius * ( 1 - 1/cos( alpha ) ) ) );
 
     return delta;
 }