Colin Walters authored Jun 23, 2016 and Philip Withnall committed Jan 15, 2018

This is a variant of g_file_get_path() which returns a const string to
the caller, rather than transferring ownership.

I've been carrying `gs_file_get_path_cached()` in libgsystem and it
has seen a lot of use in the ostree and flatpak codebases.  There are
probably others too.

I think language bindings like Python/Gjs could also use this to avoid
an extra malloc (i.e. we could transparently replace
`g_file_get_path()` with `g_file_peek_path()`.

(Originally by Colin Walters. Tweaked by Philip Withnall to update to
2.56, change the function name and drop the locking.)

https://bugzilla.gnome.org/show_bug.cgi?id=767976