Re: continuing excessive parallelism building go

I have committed a fix.

I left out the setting of MAKE_JOBS_SAFE because I concur with Jonathan
that it would be wrong.

I'll let this sit for 3 days and if no issues will apply it to the other
lang/go1* packages where it fits (i.e., if they are overly aggressive
and the package builds with this).

I believe that this issue is only in the compilers now, because this
sort of instruction has been in the mk used by go programs for a while.