[oe] gvfs issues

[Andreas Müller]

Hi,

a while back issues with current XFCE were reported in
meta-raspberrypi [1]. One symptom was mentioned which I see now either
on master (did not have it on thud):

| It takes a long time to visualize the background. Does not let in
the Xfce-terminal.

I looked into this and know what is causing it. In journal there are
complaints that gvfs-udisks2-volume-monitor cannot be started due to
missing permission. That is correct: this and other executables
shipped by gvfs are missing executable flags. Setting flags manually
fixes the problem.

Have not analysed this more deeply but:
* Seems the files get correct flags when building from scratch
* I suspect the build system change from autotools -> meson might be a
place to look in.

Will check further

[1] https://github.com/agherzan/meta-raspberrypi/issues/364#issuecomment-472439863

Andreas