[Bug go/83308] Missing platform definitions for SH in libgo

[olegendo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83308

--- Comment #3 from Oleg Endo <olegendo at gcc dot gnu.org> ---
Go will not work on SH just by adding it to the list of targets.  For instance
split stacks support is not implemented on SH.