Move dependencies in 'external' directory and pdate git submodules

external/Catch2/fuzzing/NullOStream.cpp

@@ -0,0 +1,18 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+#include "NullOStream.h"
+
+void NullOStream::avoidOutOfLineVirtualCompilerWarning()
+{
+}
+
+int NullStreambuf::overflow(int c){
+    setp(dummyBuffer, dummyBuffer + sizeof(dummyBuffer));
+    return (c == traits_type::eof()) ? '\0' : c;
+}