Allow building as a relocatable library

[onox]

I have a library project .gpr file that with "sdlada". If sdlada is built as a static library then I get the following error: cannot import static library project "sdlada".

If I change Library_Kind in build/gnat/sdlada.gpr to "relocatable", then the error disappears.

[Lucretia]

Is this still an issue, I removed the relocatable build ages ago in favour of just having a static build to reduce the number of libs people would need to distribute if they were to distribute their app/game binary only.