MINOR: check: report error on incompatible connect proto

Report an error when using an explicit proto for a connect rule with
non-compatible mode in regards with the selected check type (tcp-check
vs http-check).
diff --git a/src/tcpcheck.c b/src/tcpcheck.c
index 3142e78..75d97f3 100644
--- a/src/tcpcheck.c
+++ b/src/tcpcheck.c
@@ -2282,6 +2282,16 @@
 				memprintf(errmsg, "'%s' : unknown MUX protocol '%s'.", args[cur_arg], args[cur_arg+1]);
 				goto error;
 			}
+
+			if (strcmp(args[0], "tcp-check") == 0 && mux_proto->mode != PROTO_MODE_TCP) {
+				memprintf(errmsg, "'%s' : invalid MUX protocol '%s' for tcp-check", args[cur_arg], args[cur_arg+1]);
+				goto error;
+			}
+			else if (strcmp(args[0], "http-check") == 0 && mux_proto->mode != PROTO_MODE_HTTP) {
+				memprintf(errmsg, "'%s' : invalid MUX protocol '%s' for http-check", args[cur_arg], args[cur_arg+1]);
+				goto error;
+			}
+
 			cur_arg++;
 		}
 		else if (strcmp(args[cur_arg], "comment") == 0) {