qga: Fix guest-get-fsinfo error API violations

build_guest_fsinfo_for_virtual_device() dereferences @errp when
build_guest_fsinfo_for_device() fails.  That's wrong; see the big
comment in error.h.  Introduced in commit 46d4c5723e "qga: Add
guest-get-fsinfo command".

No caller actually passes null.

Fix anyway: splice in a local Error *err, and error_propagate().

Cc: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20191204093625.14836-10-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
1 file changed