feat(arm): Makefile add armv6 and arm64 to releases

[karlskewes]

Description

Update release target of Makefile to include building armv6 and arm64 binaries.

Note: it seems possible to build all binaries on amd64 or armv6 (with dep changes).

Motivation and Context

On path to close #16 .

Docker images to come later.

How Has This Been Tested?

On armv7 RPi 3B tested version/etc. Not doing full proxy workflow:

karl@pi1:~ $ ./oauth2_proxy-linux-armv6 
2019/02/01 08:33:17 main.go:107: Invalid configuration:
  missing setting: cookie-secret
  missing setting: client-id
  missing setting: client-secret
  missing setting for email validation: email-domain or authenticated-emails-file required.
      use email-domain=* to authorize all email addresses

karl@pi1:~ $ ./oauth2_proxy-linux-armv6 --version
oauth2_proxy v3.0.0-17-g090ff11-dirty (built with go1.11.5)

Same again on arm64 Rock64 SBC:

rock64@k8s-w-01:~$ ./oauth2_proxy-linux-arm64 
2019/02/01 08:34:19 main.go:107: Invalid configuration:
  missing setting: cookie-secret
  missing setting: client-id
  missing setting: client-secret
  missing setting for email validation: email-domain or authenticated-emails-file required.
      use email-domain=* to authorize all email addresses

rock64@k8s-w-01:~$ ./oauth2_proxy-linux-arm64 --version
oauth2_proxy v3.0.0-17-g090ff11-dirty (built with go1.11.5)

Checklist:

• My change requires a change to the documentation or CHANGELOG.
• I have updated the documentation/CHANGELOG accordingly.
• I have created a feature (non-master) branch for my PR.

[JoelSpeed]

Looks good, just one quick question to help my understanding (not an arm user)

[JoelSpeed]

Am I right in thinking that if we changed this to GOARM=7 then it wouldn't run on original Pi's and Pi zeros whereas currently it runs on all Pi's?

[kfox1111]

I believe that is correct. It allows new v7 only asm instructions to be used for the build that the zero doesn't have. v7 is a superset of v6.

[karlskewes]

Indeed.
With go and dep dependencies I decided to just leave this at armv6 for now.
As it builds and runs on my armv7 I figure it's safe to start with.

[JoelSpeed]

LGTM thanks