Split out Catch::cout/cerr/clog into their own file

tests/ExtraTests/X04-DisabledExceptions-CustomHandler.cpp

@@ -8,11 +8,13 @@
 
 #include <catch2/catch_test_macros.hpp>
 
+#include <iostream>
+
 namespace Catch {
     [[noreturn]]
     void throw_exception(std::exception const& e) {
-        Catch::cerr() << "====== CUSTOM HANDLER ====== run terminates because an exception was thrown.\n"
-                      << "The message was: " << e.what() << '\n';
+        std::cerr << "====== CUSTOM HANDLER ====== run terminates because an exception was thrown.\n"
+                  << "The message was: " << e.what() << '\n';
         // Avoid abort and other exceptional exits -- there is no way
         // to tell CMake that abort is the desired outcome of a test.
         exit(1);