fixed includedir not being relative from the cfg.workspace.location

[LostbBlizzard]

this is missing for the forceincludes.

from Jarod42

Paths (as includedirs) from toolset should be fixed now when workspace location != project location.

I check and it does seem to be working for my project can you show the lines of code that would have fix this issue.

[Jarod42]

https://github.com/jimon/premake-ninja/pull/33 should have fix it. requires master branch of premake though.