nginxModules.vts: fix build on gcc11

pkgs/servers/http/nginx/generic.nix

@@ -107,6 +107,8 @@ stdenv.mkDerivation {
   NIX_CFLAGS_COMPILE = toString ([
     "-I${libxml2.dev}/include/libxml2"
     "-Wno-error=implicit-fallthrough"
+    # fix build vts module on gcc11
+    "-Wno-error=stringop-overread"
   ] ++ optional stdenv.isDarwin "-Wno-error=deprecated-declarations");
 
   configurePlatforms = [];