mesa: build libOSMesa into $osmesa output
libdrm: minor update 2.4.46 -> .48
pixman: major update 0.30.2 -> 0.32.2

This is new major release with performance improvements for image scaling,
and a large number of bug fixes.
glib: bugfix update 2.38.0 -> .2
icu: update 51.1 -> 52.1
harfbuzz: major update 0.9.12 -> .24

Also use deps recommended by upstream (by defaul).
libusb1: update 1.0.16 -> .17
gnome3.at_spi2_*: bugfix update 2.10.0 -> .2
gdk_pixbuf: bugfix update 2.30.0 -> .1
gtk3: bugfix updates 3.10.0 -> .4
libssh: bugfix update + CVE-2013-0176

It seems an old DoS-only problem.
libgsf: bugfix update 1.14.26 -> .28
dbus_python: update 1.1.1 -> 1.2.0
desktop_file_utils: update
imagemagick: minor update 6.8.7-5 -> .7-6
gvfs: major update 1.14.2 -> 1.18.3, unify to one

There were several files defining gvfs, now use one common.
Also delete long-unused forgotten xfce file.
libunique: fix build, make the package unique

The one in gnome2 was failing to build,
but all there is likely in a desolate state anyway.

In gmpc it also seemed without any reason to have a duplicate.