* src/proxy_internal.c, src/qemu_internal.c, src/test.c,
src/xen_unified.c, src/xend_internal.c, src/xs_internal.c:
During virConnectOpen, be careful to call __virRaiseError
with conn = NULL so that the error message is not
discarded.
* src/xen_unified.c: In the non-root case keep track of the
Xen underlying drivers which opened correctly and only
try methods on those opened drivers.
* src/xen_unified.c (xenUnifiedRegister): Comment the
xenUnifiedRegister function to avoid error message
when building docs/. Patch from Atsushi SAKAI.