[Bug c/89734] const qualifier on return type not erased inside __typeof__

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89734

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot 
com> ---
This doesn't need typeof.  The following much simpler test demonstrates 
this regression.

typedef const int CI;
CI f (void);
const int f (void);