BUG/MINOR: ssl: Fix external function in order not to return a pointer on an internal trash buffer.

'ssl_sock_get_common_name' applied to a connection was also renamed
'ssl_sock_get_remote_common_name'. Currently, this function is only used
with protocol PROXYv2 to retrieve the client certificate's common name.
A further usage could be to retrieve the server certificate's common name
on an outgoing connection.
(cherry picked from commit 0abf836ecb32767fa1f9ad598f3e236e073491bd)
diff --git a/src/connection.c b/src/connection.c
index 0b154d8..20a911b 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -682,9 +682,8 @@
 				tlv->verify = htonl(ssl_sock_get_verify_result(remote));
 			}
 			if (srv->pp_opts & SRV_PP_V2_SSL_CN) {
-				value = ssl_sock_get_common_name(remote);
-				if (value) {
-					tlv_len = make_tlv(&buf[ret+ssl_tlv_len], (buf_len - ret - ssl_tlv_len), PP2_TYPE_SSL_CN, strlen(value), value);
+				if (ssl_sock_get_remote_common_name(remote, &trash) > 0) {
+					tlv_len = make_tlv(&buf[ret+ssl_tlv_len], (buf_len - ret - ssl_tlv_len), PP2_TYPE_SSL_CN, trash.len, trash.str);
 					ssl_tlv_len += tlv_len;
 				}
 			}