Supporting UNIX sockets in address matching.

This closes #645 issue on GitHub.

(Also moved a changelog line that was misplaced in a previous commit.)

src/nxt_conf_validation.c

@@ -2157,6 +2157,11 @@ nxt_conf_vldt_match_addr(nxt_conf_validation_t *vldt,
         return nxt_conf_vldt_error(vldt, "The \"address\" does not support "
                                          "IPv6 with your configuration.");
 
+    case NXT_ADDR_PATTERN_NO_UNIX_ERROR:
+        return nxt_conf_vldt_error(vldt, "The \"address\" does not support "
+                                         "UNIX domain sockets with your "
+                                         "configuration.");
+
     default:
         return nxt_conf_vldt_error(vldt, "The \"address\" has an unknown "
                                          "format.");