gdb-many-windows enables an IDE like debugger frontend for Emacs.
New name is `c-c++-default-mode-for-headers`, possible values are `c-mode` or `c++-mode`.
Remove default auto-mode-alist mapping from *.h to c++-mode. Introduce a variable and use that in the init: section of cc-mode to conditionally update the auto-mode-alist. Updated the documentation. Conflicts: contrib/!lang/c-c++/README.md