Squelch 'eof from qemu monitor' error on normal VM shutdown

[Jim Fehlig]

Hi All,

Likely Christian received a bug report that motivated commit aeda1b8c56, which 
was later reverted by Michal with commit 72adaf2f10. In the past, I recall being 
asked about "internal error: End of file from qemu monitor" on normal VM 
shutdown and gave a hand wavy response using some of Michal's words from the 
revert commit message.

I recently received a bug report (sorry, but no public link) from a concerned 
user about this error and wondered if there is some way to improve it? I went 
down some dead ends before circling back to Christian's patch. When rebased to 
latest master, I cannot reproduce the hangs reported by Michal [1]. Perhaps 
Nikolay's series to resolve hangs/crashes of libvirtd [2] has now made 
Christian's patch viable?

Regards
Jim

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1536461
[2] https://listman.redhat.com/archives/libvir-list/2020-July/msg01606.html