[Bug preprocessor/16358] -Wno-system-headers hides warning caused by user header vs system header conflict

[niva at niisi dot msk.ru]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=16358

--- Comment #11 from niva at niisi dot msk.ru ---
(in reply to Martin Sebor in comment #10)

Implementation of -Wmacro-redefined (with possibility of turning this warning
to error) would solve the problem of our users.