Getting the canonical filename is a relatively common
operation when dealing with symbolic links.
This commit exposes GLocalFile's implementation of a
filename canonicalizer function, with a few additions
to make it more useful for consumers of it.
Instead of always assuming g_get_current_dir(), the
exposed function allows passing it as an additional
parameter.
This will be used to fix the GTimeZone code to retrieve
the local timezone from a zoneinfo symlink.
(Tweaked by Philip Withnall <withnall@endlessm.com> to drop g_autofree
usage and add some additional tests.)
https://bugzilla.gnome.org/show_bug.cgi?id=111848
b9b642de06