[Bug c/68412] [6 Regression] ICE with -Wall -Wextra in fold_binary_loc()

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68412

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
C_MAYBE_CONST_EXPR leaks into the ME.