Fix copying SockAddr struct

Valgrind alerted about accessing uninitialized bytes after commit
4945e4e:

==700242== VALGRINDERROR-BEGIN
==700242== Conditional jump or move depends on uninitialised value(s)
==700242==    at 0x6D8A2A: getnameinfo_unix (ip.c:253)
==700242==    by 0x6D8BD1: pg_getnameinfo_all (ip.c:122)
==700242==    by 0x4B3EB6: BackendInitialize (postmaster.c:4266)
==700242==    by 0x4B684E: BackendStartup (postmaster.c:4114)
==700242==    by 0x4B6986: ServerLoop (postmaster.c:1780)
==700242==    by 0x4B80CA: PostmasterMain (postmaster.c:1478)
==700242==    by 0x3F7424: main (main.c:197)
==700242==  Uninitialised value was created by a stack allocation
==700242==    at 0x4B6934: ServerLoop (postmaster.c:1737)
==700242==
==700242== VALGRINDERROR-END

That was because the SockAddr struct was not copied correctly.

Per buildfarm animal "skink".

Author: hlinnaka

src/backend/libpq/pqcomm.c

@@ -177,7 +177,8 @@ pq_init(ClientSocket *client_sock)
 	/* allocate the Port struct and copy the ClientSocket contents to it */
 	port = palloc0(sizeof(Port));
 	port->sock = client_sock->sock;
-	port->raddr = client_sock->raddr;
+	memcpy(&port->raddr.addr, &client_sock->raddr.addr, client_sock->raddr.salen);
+	port->raddr.salen = client_sock->raddr.salen;
 
 	/* fill in the server (local) address */
 	port->laddr.salen = sizeof(port->laddr.addr);