[Bug go/46986] Go is not supported on Darwin

[ian at airs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46986

--- Comment #46 from Ian Lance Taylor <ian at airs dot com> ---
A small bit of work is needed on the codegen, to read and write the export
data.  And some work is required on the runtime, to clean it up to support
Darwin.  It has to be done by someone with access to a modern Darwin system.