[Bug sanitizer/83219] [8 regression] c-c++-common/ubsan/unreachable-2.c fails starting with r255201

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83219

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 42751
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42751&action=edit
gcc8-pr83219.patch

Untested fix.