bug#6781: emacs server with X11 build on OSX

[Leo <sdl.web@gmail.com>]

,----
| (make-network-process :name "server" :server t :family 'ipv4 :service t :host 'local).
`----

Fails with backtrace:
,----
| Debugger entered--Lisp error: (error "localhost/0 nodename nor servname provided, or not known")
|   make-network-process(:name "server" :server t :family ipv4 :service t :host local)
|   eval((make-network-process :name "server" :server t :family (quote ipv4) :service t :host (quote local)))
|   eval-last-sexp-1(nil)
|   eval-last-sexp(nil)
|   call-interactively(eval-last-sexp nil nil)
`----

and
,----
| (make-network-process :name "server" :server t :family 'ipv4 :service t :host "localhost")
`----
fails in the same way.

However, the following works:
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| (make-network-process :name "server" :server t :family 'ipv4 :service t :host "127.0.0.1")
`----


`ping localhost' in terminal shows:
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| leo@Victoria ~$ ping localhost
| PING localhost (127.0.0.1): 56 data bytes
| 64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.041 ms
| 64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.049 ms
`----

Leo