if(WIN32) guard is missed for many projects in ROS2

[Peter9606]

@wjwwood

Actually it also affects the _LOCAL visibility macro even on posix machines. So it should always be set, imo. Perhaps it could be given a more generic name that doesn’t contain dll. I think we may have even done this in a couple of packages.

Then it’s better to make a model in ROS2’s core pojects, so that when people are porting other projects could always have right samples.