daemon: print parameters for vgchange in error messages
daemon: grub: show grub-install's output on error if verbose
appliance: init: properly set PS1 and TERM for virt-rescue (RHBZ#812970).

Setting environment variables such as PS1 for bash before starting it
might not be effective when the startup scripts provided by the
distribution unconditionally change it.
Hence, set PS1 and TERM in a ~/.bashrc, which will be source'd last and
thus be able to set them the way we want.
launch: libvirt: Only use serial BIOS (sgabios) on x86.

This device is not present at least on ARM.  Unfortunately libvirt
doesn't give us any way to query when the device is present.

This fixes commit bed592498d791c5ce6ad722f41dcbfbe243b0a7a.
Version 1.27.15.