GitLab

AIX doesn't allow to mmap an address range which is already mmap.
Therefore, once the region has been allocated, it must munmap before
being able to play with it.

Change-Id: I1547782f0379024f57869f1dda8c1c9bb12d831f
Reviewed-on: https://go-review.googlesource.com/c/go/+/174059

Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>