Expand the userdir in the configured path so a user can use e.g.
path=~/sysroots in sysroot.conf

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Philip Withnall <philip.withnall@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D4875