The test for #9400 relies on an assembler function that manipulates
the stack pointer. Meanwile, it uses a global variable for
synchronization. However, position independent code on 386 use a
function call to fetch the base address for global variables.
That function call in turn overwrites the Go stack.

Fix that by fetching the global variable address once before the
stack register manipulation.

Fixes the android/386 builder.

Change-Id: Ib77bd80affaa12f09d582d09d8b84a73bd021b60
Reviewed-on: https://go-review.googlesource.com/23683
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>