[Bug bootstrap/93409] [10 Regression] gcn libgomp plugin fails to build for x32

[doko at ubuntu dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93409

--- Comment #3 from Matthias Klose <doko at ubuntu dot com> ---
this is needed for the bootstrap, you have to build the plugin for all
multilibs, although it's discarded on install.