alertmanager container hase some error under mips64 #2271

### What did you do?
First run "make build"，in order to adaptation “mips64” I modify the Dockerfile
What did you expect to see?
I hope alertmanager container can normal operation under mips64 architecture
What did you see instead? Under which circumstances?
it shows some error
#level=info ts=2020-05-29T09:53:40.605Z caller=main.go:231 msg="Starting Alertmanager" version="(version=0.20.0, branch=HEAD, revision=f74be0400a6243d10bb53812d6fa408ad71ff32d)"
#level=info ts=2020-05-29T09:53:40.606Z caller=main.go:232 build_context="(go=go1.13.6, user=root@bogon, date=20200529-07:00:14)"
#level=warn ts=2020-05-29T09:53:40.608Z caller=cluster.go:154 component=cluster err="couldn't deduce an advertise address: no private IP found, explicit advertise addr not provided"
#level=error ts=2020-05-29T09:53:40.611Z caller=main.go:256 msg="unable to initialize gossip mesh" err="create memberlist: Failed to get final advertise address: No private IP address #found, and explicit IP not provided"

This problem has been discussed in the community.#1434 It is said that the problem has been solved. However, this problem still exists in "MIPS64". Currently, it can be configured in the dockerfile "--cluster.advertise-Address=127.0.0.1:9093". Can I directly use patch to avoid problems in the source code
Environment
[root@os-kvm1 alertmanager]# uname -a
Linux os-kvm1 3.10.0-1127.8.2.el7.x86_64 #1 SMP Tue May 12 16:57:42 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
* System information:
[root@os-kvm1 alertmanager]# uname -srm
Linux 3.10.0-1127.8.2.el7.x86_64 x86_64
Alertmanager version:
alertmanager-0.20.0
* Prometheus version:
prometheus-2.17.2