IWYU: Update for Debian 13 CI job

`include-what-you-use` diagnostics, in practice, are specific to
the environment's compiler and standard library.  Update includes
to satisfy IWYU for our CI job under Debian 13.  Some patterns:

* Types named in virtual `override` signatures no longer require
  includes since the overridden signature already names them.

* A function argument's type needs to be included even if its constructor
  is called only by implicit conversion.  For example, constructing a
  `std::function` from a lambda now requires `<functional>`.

* Some prior mysterious `<type_traits>` inclusions are no longer required.

Source/cmGeneratorTarget_CompatibleInterface.cxx

@@ -7,6 +7,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cerrno>
+#include <cstddef>
 #include <cstdlib>
 #include <cstring>
 #include <iterator>