Commit 119cd06 started setting the primary bool for the first
user-specified video even if user omitted the 'primary' attribute.
However this was done before the addition of the implicit device.
This broke startup of transient qemu domains with no <video>:
https://bugzilla.redhat.com/show_bug.cgi?id=1325757
Move this default to virDomainDefPostParseInternal,
after the addition of the implicit video device, to catch the implicit
video as well.
A user was having an issue with this specific VMWare Fusion config and
he gave me permission to add it as part of our test suite to further
expand our VMX test coverage. Unfortunately our VMX parser and
generator does not support many features contained within and just
silently ignores fields it does not understand so they had to
be removed out in the xml2vmx test. The original unmodified version
exists in the vmx2xml test.