Fixed a minor syntax error tripping some C++ compilers

Author: AngusJohnson

CPP/Clipper2Lib/src/clipper.offset.cpp

@@ -594,7 +594,7 @@ void ClipperOffset::DoGroupOffset(Group& group)
 
 // when shrinking outer paths, make sure they can shrink this far (#593)
 // also when shrinking holes, make sure they too can shrink this far (#715)
-if (group_delta_ > 0 == ToggleBoolIf(*is_hole_it, group.is_reversed) &&
+if ((group_delta_ > 0) == ToggleBoolIf(*is_hole_it, group.is_reversed) &&
 (std::min(path_rect_it->Width(), path_rect_it->Height()) <= -group_delta_ * 2) )
  continue;