[Bug lto/60981] lto-plugin configuration doesn't test for -static-libgcc (OSX gcc -> clang)

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60981

--- Comment #5 from Rainer Orth <ro at gcc dot gnu.org> ---
Created attachment 32790
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32790&action=edit
proposed patch