backward -> deprecated

[Gabriel Dos Reis]

Benjamin Kosnik <bkoz@redhat.com> writes:

[...]

| Phil, Alexandre, and Jason have all indicated some kind of warning for
| using the backward headers, unless a specific (already existing)
| warning flag is used. To me, this means some kind of macro definition
| triggered via this flag (done in cpp a la _EXCEPTIONS)
| 
| Then, we could add a third directory to the g++ include search patch
| (a la the target include work) for backward headers, search it, and
| install the contents of the backward directory into it.
| 
| Sound reasonable? Other approaches that I've missed that would be easier?

Your proposal sounds reasonable to me.  I'm not a cpplib guru so I
guess we'll need Neil's input as to how to proceed.

-- Gaby