If the compiler has a non-devel version it will report that version
to the go command for use as the "compiler ID" instead of using
the content ID of the binary. This in turn allows the go command
to see the compiled-for-amd64 arm compiler and the compiled-for-arm
arm compiler as having the same ID, so that packages cross-compiled
from amd64 look up-to-date when copied to the arm system
during the linux-arm buildlets and trybots.

Change-Id: I76cbf129303941f8e31bdb100e263478159ddaa5
Reviewed-on: https://go-review.googlesource.com/74360
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>