domain_conf.c: avoid a leak and the need for "cleanup:" block

domain_conf.c: avoid a leak and the need for "cleanup:" block

* src/conf/domain_conf.c (virDomainChrDefFormat): Plug a leak on
an error path, and at the same time, eliminate the need for a
"cleanup:" block.  Before, the "return -1" after the switch
would leak an "addr" string.  Now, by reversing the port,addr-
getting blocks we can free "addr" immediately and skip the goto.