Use correct include path, should fix #415

[paulmelis]

No description provided.

[johguenther]

Unfortunately this is not robust enough as is breaks the "normal" build. Looking for alternatives.

[paulmelis]

Strange that the build fails, as I rebuilt locally after the change to check. But maybe that's because I rebuilt as part of the superbuild

[johguenther]

I found the superbuild tricky to test changes: even with ALWAYS_REBUILD=ON a rebuild is not triggered reliably. The only way to be really sure is to nuke the whole build folder.

[paulmelis]

Right, I indeed clean it out when needed with extra time used for that. I guess I could install ccache as some sort of a workaround, as I feel the non-superbuild is a bit tricky to do in keeping all dependencies correct in terms of versions.