s4 lib socket: Ensure address string owned by parent struct

The local address string was not owned by it's parent structure, which
caused a use after free error in
continue_ip_open_socket source4/librpc/rpc/dcerpc_sock.c:267

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13929

Signed-off-by: Gary Lockyer <[email protected]>
Reviewed-by: Andrew Bartlett <[email protected]>

Autobuild-User(master): Andrew Bartlett <[email protected]>
Autobuild-Date(master): Wed May  8 20:03:42 UTC 2019 on sn-devel-184

(cherry picked from commit ae9fb933)
22 jobs for gary-bug-13929-v4-10 in 209 minutes and 31 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Build
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build_others

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build_samba

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build_samba_ad_dc_backup_py2

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build_samba_buildpy2_only

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build_samba_ctdb

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build_samba_libs

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build_samba_libs_py2

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