configs/*: add VM guest packages and enable their services

* virtualbox-guest-utils-nox package and vboxservice.service for VirtualBox.
* qemu-guest-agent package and qemu-guest-agent.service for QEMU & libvirt.

Implements #118.

configs/baseline/airootfs/etc/systemd/system/multi-user.target.wants/qemu-guest-agent.service

+/usr/lib/systemd/system/qemu-guest-agent.service
\ No newline at end of file

configs/baseline/airootfs/etc/systemd/system/multi-user.target.wants/vboxservice.service

+/usr/lib/systemd/system/vboxservice.service
\ No newline at end of file

configs/baseline/packages.x86_64

@@ -6,4 +6,6 @@ linux
 mkinitcpio
 mkinitcpio-archiso
 openssh
+qemu-guest-agent
 syslinux
+virtualbox-guest-utils-nox

configs/releng/airootfs/etc/systemd/system/multi-user.target.wants/qemu-guest-agent.service

+/usr/lib/systemd/system/qemu-guest-agent.service
\ No newline at end of file

configs/releng/airootfs/etc/systemd/system/multi-user.target.wants/vboxservice.service

+/usr/lib/systemd/system/vboxservice.service
\ No newline at end of file

configs/releng/packages.x86_64

@@ -79,6 +79,7 @@ partimage
 pcsclite
 ppp
 pptpclient
+qemu-guest-agent
 reflector
 reiserfsprogs
 rp-pppoe
@@ -103,6 +104,7 @@ usb_modeswitch
 usbmuxd
 usbutils
 vim
+virtualbox-guest-utils-nox
 vpnc
 wireless-regdb
 wireless_tools