xcursor: check that XDG base directory path is absolute

Antonin Décimo requested to merge MisterDA/wlroots:xdg into master

The spec reads:

All paths set in these environment variables must be absolute. If an implementation encounters a relative path in any of these variables it should consider the path invalid and ignore it.


If $XDG_DATA_HOME is either not set or empty, a default equal to $HOME/.local/share should be used.

Testing that the path is absolute also entails that is is non-empty.

Merge request reports