BUG/MINOR: server: make "agent-addr" work on default-server line

As reported in issue #408, "agent-addr" doesn't work on default-server
lines. This is due to the transcription of the old "addr" option in commit
6e5e0d8f9e ("MINOR: server: Make 'default-server' support 'addr' keyword.")
which correctly assigns it to the check.addr and agent.addr fields, but
which also copies the default check.addr into both the check's and the
agent's addr fields. Thus the default agent's address is never used.

This fix makes sure to copy the check from the check and the agent from
the agent. However it's worth noting that if "addr" is specified on the
server line, it will still overwrite both the check and the agent's
addresses.

This must be backported as far as 1.8.

(cherry picked from commit 2444108f16868ccde928d97ffa3db847ddad89fb)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit 3834754e654fa41491916a2e23c5fbe9b4ba5d82)
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/src/server.c b/src/server.c
index 236d6ba..064d374 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1732,7 +1732,8 @@
 		srv->cklen  = src->cklen;
 	}
 	srv->use_ssl                  = src->use_ssl;
-	srv->check.addr = srv->agent.addr = src->check.addr;
+	srv->check.addr               = src->check.addr;
+	srv->agent.addr               = src->agent.addr;
 	srv->check.use_ssl            = src->check.use_ssl;
 	srv->check.port               = src->check.port;
 	srv->check.sni                = src->check.sni;