Set 'wait-for-session=1' for 'qubes.VMShell+WaitForSession'

This is intended to be used for DispVMs for which only a single RPC call
can be made before they are destroyed.

Fixes QubesOS/qubes-issues#3012

debian/qubes-core-agent.install

@@ -42,6 +42,7 @@ etc/qubes/rpc-config/qubes.SelectFile
 etc/qubes/rpc-config/qubes.SelectDirectory
 etc/qubes/rpc-config/qubes.StartApp
 etc/qubes/rpc-config/qubes.InstallUpdatesGUI
+etc/qubes/rpc-config/qubes.VMShell+WaitForSession
 etc/qubes/suspend-post.d/README
 etc/qubes/suspend-post.d/*.sh
 etc/qubes/suspend-pre.d/README

qubes-rpc/qubes.VMShell+WaitForSession.config

@@ -0,0 +1 @@
+wait-for-session=1

rpm_spec/core-agent.spec

@@ -591,6 +591,7 @@ rm -f %{name}-%{version}
 %config(noreplace) /etc/qubes/rpc-config/qubes.SelectDirectory
 %config(noreplace) /etc/qubes/rpc-config/qubes.StartApp
 %config(noreplace) /etc/qubes/rpc-config/qubes.InstallUpdatesGUI
+%config(noreplace) /etc/qubes/rpc-config/qubes.VMShell+WaitForSession
 %dir /etc/qubes/autostart
 %config(noreplace) /etc/default/grub.qubes
 /etc/qubes/autostart/README.txt