This does not have any effect in practice since the option -g
(originally meant for GCC extensions to the C standards) implicitly
allows all features from C11, since err.c 1.111 from 2021-04-14.
Since the default lint flags for NetBSD builds include the option -g,
this allows all C11 features.
Currently it is not possible to say "allow GNU extensions but not C11".
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