[Bug c/83421] GCC give better error when 32bit x86 libs not found

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83421

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
GCC can't know why that header is missing, and it can't recommend
Ubuntu-specific packages.