[Qt-creator] Opening files from error messages

[Kris Wong]

I've noticed that when I open a file by clicking on it in the Build Issues view, it doesn't correctly pick up the encoding from the project setting the file belongs to. This is very inconvenient when there are a lot of build errors to fix. Of course, the file could belong to more than one project, but a file only has one encoding no matter how many projects it's in. If it doesn't belong to a project, just handle it as it's handled currently.

Kris Wong