[Bug bootstrap/80779] MPX bootstrap does not work on real hardware supporting that

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80779

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Created attachment 41365
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41365&action=edit
Semi-working patch for bootstrap