According to Go execution modes, a Go program compiled with
-buildmode=c-archive has a main function, but it is ignored on run.
This gives the runtime the information it needs not to run the main.

I have this working with pending linker changes on darwin/amd64.

Change-Id: I49bd7d65aa619ec847c464a872afa5deea7d4d30
Reviewed-on: https://go-review.googlesource.com/8701Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>