client: Remove inconsistencies between async and sync variants
client: Remove inconsistencies between async and sync variants

The async implementation of find_enclosing_mount does not assume that
there is a GMountInfo when no error has occurred.

https://bugzilla.gnome.org/show_bug.cgi?id=739075

gicmo/gvfs,gicmo/gvfs,gicmo/gvfs,gicmo/gvfs