[Bug c/81404] suggested hints for standard C macros should avoid GCC predefined macros

[schwab@linux-m68k.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81404

--- Comment #2 from Andreas Schwab <schwab@linux-m68k.org> ---
Probably all reserved identifiers should be discuraged for fixit hints.