This is enough to let libgo build when configured using
    --with-multilib-list=m64,m32,mx32.  I don't have an x32-enabled kernel
    so I haven't tested whether it executes correctly.
    
    For https://gcc.gnu.org/PR87470
    
    Reviewed-on: https://go-review.googlesource.com/138817

From-SVN: r264772