* src/bridge.c (brAddTap): Remove redundant errno=ENOMEM assignment
after failed strdup.
* src/cgroup.c (virCgroupFree): Remove redundant *group=NULL assignment
after VIR_FREE(*group).
* src/lxc_driver.c (lxcShutdown): Likewise.
* src/xen_unified.c (xenUnifiedClose): Likewise.
* src/xm_internal.c (xenXMDomainConfigFormat): Rewrite disk-
and net-config-setting code to be clearer.