...so that LO shares the credentials with Nautilus once the connection has been
set up in Nautilus.

The reason the (non-standard) dav, davs URLs used by GNOME's old GnomeVFS and
successor GVFS/GIO were handled via LO's webdav UCP rather than the GNOME-
specific gnomevfs resp. gio UCP since b07a5fcc
"INTEGRATION: CWS tkr10: i84676 neon and gnome-vfs2" is discussed at
<https://bz.apache.org/ooo/show_bug.cgi?id=84676> "mixing neon and the hidden
embedded contents old [sic] another neon inside libhttp.so of gnome-vfs2 is
unreliable" and only pertains to the legacy gnomevfs UCP, not the new gio one.
So keep handling dav, davs URLs via LO's internal webdav UCP under legacy
--enable-gnome-vfs, but handle them via the GNOME-specific gio UCP under the
default --enable-gio.

Change-Id: Ib132168701a7ae0a7dcabdead6a299eda0cd4594