[CPPRT] Add cpprt for GCC, tool

- Link it to libsup++
- Add __cxa_pure_virtual

sdk/lib/cpprt/__cxa_pure_virtual.cpp

@@ -0,0 +1,13 @@
+/*
+ * PROJECT:     ReactOS C++ runtime library
+ * LICENSE:     MIT (https://spdx.org/licenses/MIT)
+ * PURPOSE:     __cxa_pure_virtual implementation
+ * COPYRIGHT:   Copyright 2024 Timo Kreuzer <timo.kreuzer@reactos.org>
+ */
+
+#include <intrin.h>
+
+extern "C" void __cxa_pure_virtual(void)
+{
+    __debugbreak();
+}