[GtkFileChooser] Fix initial selection when hidden files are shown

[GtkFileChooser] Fix initial selection when hidden files are shown

We were breaking prematurely out of the loop that goes through
each file that is pending selection; not only does that loop
disable filtering and show hidden files if needed, but it also
selects the files themselves.  So we need to walk the whole
list of files.

Signed-off-by: Federico Mena Quintero <federico@gnome.org>
https://bugzilla.gnome.org/show_bug.cgi?id=643170