Please revert the %pure-parser deprecation message

[Peter Wu]

Hi,

Starting with Bison 3.4, use of '%pure-parser' started emitting
deprecation warnings, recommending '%define api.pure' instead. The
latter however is a non-standard directive which is not implemented by
Berkeley YACC. Berkeley YACC does implement %pure-parser instead:
https://invisible-island.net/byacc/manpage/yacc.html

Correct me if I am wrong, but it appears that the change to '%define
api.pure' is purely a stylistic one. In our project, use of '%define
api.pure [full]' makes no difference in the generated code.

Would it be possible to revert the diagnostic message? -Wno-deprecated
(added in Bison 2.7) does hide it, but that requires extra custom code.
-- 
Kind regards,
Peter Wu
https://lekensteyn.nl