Part of the testmain generation logic (sans coverage) has been taken
from go build and put into golist_fallback_testmain.go.
golist_fallback invokes this logic and builds up the package metadata
for the testmain.
The tests checking for testmain are now no longer skipped from
packages_test.go.
Change-Id: I487a947f087f3ad4161ea6c2bed06ebb2f833422
Reviewed-on: https://go-review.googlesource.com/134119
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>