Check IsAnchoringRestricted before measuring the tooltip

I received a bug report regarding LibExtraTip in my addon conflicting with another addon. The user reported the bug both to me via email and as an issue in the other addon's github:

https://github.com/seblindfors/ConsolePort/issues/145

The other addon author replied:

report to the author of that addon that they should check IsAnchoringRestricted before measuring the tooltip

I don't know enough about the tooltip system to know whether that advice is reasonable or actionable (which is why I delegate that to LibExtraTip!) but just passing that along to you in case it makes any sense. Personally, I'm not overly concerned with how quickly (or even whether) this issue gets addressed in LibExtraTip.

Thanks