If there are no parameters, there is nothing to validate.
If params == NULL, memcpy below results in memcpy(sorted, NULL, 0),
which is UB.

Found by UBSAN. Example of this codepath: virDomainBlockCopy()
(where nparams == 0 is valid) -> qemuDomainBlockCopy()

Signed-off-by: Oleg Vasilev <oleg.vasilev@virtuozzo.com>
---
 src/util/virtypedparam.c | 4 ++++
 1 file changed, 4 insertions(+)