[Bug c/85009] missing -Wdiscarded-qualifiers when dropping _Atomic

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85009

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
It's not obvious that this is a bug, in that _Atomic is syntactically a 
qualifier, but excluded semantically for most purposes.  In particular, 
that conversion is permitted by ISO C, so the _Atomic case must *not* be a 
pedwarn, even if it receives a -Wdiscarded-qualifiers warning.