qga-win: prevent crash when executing fsinfo command

qga-win: prevent crash when executing fsinfo command

The fsinfo command is currently implemented for Windows only and it's disk
parameter can be enabled by adding the define "CONFIG_QGA_NTDDSCSI" to the qga
code. When enabled and executed the qemu-ga crashed with the following message:

------------------------------------------------
File qapi/qapi-visit-core.c, Line 49

Expression: !(v->type & VISITOR_OUTPUT) || *obj)
------------------------------------------------

After some digging, turns out that the GuestPCIAddress is null and the
qapi visitor doesn't like that, so we can always allocate it instead and
initiate all it's members to -1.

Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Tomáš Golembiovský <tgolembi@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>