Add qvm-start-gui autostart script

Start it using XDG Autostart feature, but exclude starting in
qubes-session - so even if package is installed in a VM, it wont be
started simultaneusly with GUI agent.
On the other hand, if some other DE session is running there (which will
be the case for GUI domain), gui-daemons will be started accordingly.

QubesOS/qubes-issues#833

Makefile

@@ -10,3 +10,5 @@ build:
 .PHONY: install
 install:
 	$(PYTHON) setup.py install -O1 $(PYTHON_PREFIX_ARG) --root $(DESTDIR)
+	install -d $(DESTDIR)/etc/xdg/autostart
+	install -m 0644 etc/qvm-start-gui.desktop $(DESTDIR)/etc/xdg/autostart/

etc/qvm-start-gui.desktop

@@ -0,0 +1,8 @@
+[Desktop Entry]
+Name=Qubes Guid
+Comment=Starts Dom0 GUI daemon for Qubes VMs
+Icon=qubes
+Exec=qvm-start-gui
+Terminal=false
+Type=Application
+NotShowIn=X-QUBES

rpm_spec/qubes-core-mgmt-client.spec

@@ -52,6 +52,7 @@ rm -rf build
 
 %files
 %doc LICENSE
+%config /etc/xdg/autostart/qvm-start-gui.desktop
 
 %files -n python2-qubesmgmt
 %{python_sitelib}/qubesmgmt-*egg-info