MINOR: stats: Add the status code STAT_STATUS_IVAL to handle invalid requests

This patch must be backported to 1.9 because a bug fix depends on it.
diff --git a/src/proto_http.c b/src/proto_http.c
index 4361d6d..0127e23 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -84,6 +84,7 @@
 	[STAT_STATUS_NONE] = "NONE",
 	[STAT_STATUS_PART] = "PART",
 	[STAT_STATUS_UNKN] = "UNKN",
+	[STAT_STATUS_IVAL] = "IVAL",
 };
 
 /* This function handles a server error at the stream interface level. The
diff --git a/src/stats.c b/src/stats.c
index b393541..6f56353 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -2572,6 +2572,16 @@
 			              (appctx->ctx.stats.flags & STAT_NO_REFRESH) ? ";norefresh" : "",
 			              scope_txt);
 			break;
+		case STAT_STATUS_IVAL:
+			chunk_appendf(&trash,
+			              "<p><div class=active_down>"
+			              "<a class=lfsb href=\"%s%s%s%s\" title=\"Remove this message\">[X]</a> "
+			              "<b>Invalid requests (unsupported method or chunked encoded request).</b>"
+			              "</div>\n", uri->uri_prefix,
+			              (appctx->ctx.stats.flags & STAT_HIDE_DOWN) ? ";up" : "",
+			              (appctx->ctx.stats.flags & STAT_NO_REFRESH) ? ";norefresh" : "",
+			              scope_txt);
+			break;
 		default:
 			chunk_appendf(&trash,
 			              "<p><div class=active_no_check>"