Fix and test round-trip of query parameters

Fix and test round-trip of query parameters

When qparams support was dropped in commit bc1ff160, we forgot
to add tests to ensure that viruri can do the same round trip
handling of a URI. This round trip was broken, due to use
of the old 'query' field of xmlUriPtr, instead of the new
'query_raw'

Also, we forgot to report an OOM error.

* tests/viruritest.c (mymain): Add tests based on just-deleted
qparamtest.
(testURIParse): Allow difference in input and expected output.
* src/util/viruri.c (virURIFormat): Add missing error. Use
  query_raw, instead of query for xmlUriPtr object.