Support for arm containers on m1 mac

[janosmiko]

Hi,

I'm building varnish containers for amd64 and arm64 using this vmod. While it's working well on amd64 and it also works well when I'm using an arm64 linux server it's not working for desktop users using m1 mac.

They got the following error:

Error:
varnish_1        | Message from VCC-compiler:
varnish_1        | Could not open VMOD dynamic
varnish_1        |  File name: /usr/lib/varnish/vmods/libvmod_dynamic.so
varnish_1        |  dlerror: /usr/lib/varnish/vmods/libvmod_dynamic.so: undefined symbol: vmb_pthread
varnish_1        | ('/etc/varnish/default.vcl' Line 5 Pos 8)
varnish_1        | import dynamic;
varnish_1        | -------#######-
varnish_1        | 

The Dockerfile I'm using: https://github.com/rewardenv/reward/blob/main/images/varnish/debian/6.5/Dockerfile

Related issue: https://github.com/rewardenv/reward/issues/17

[gquintard]

I had the same issue while building the docker image, the fix is twofold:

• align vmb.h with the one from varnish
• add AC_CHECK_HEADERS([stdatomic.h]) to configure.ac

here's the implementation in the docker repo: https://github.com/varnish/docker-varnish/commit/e507d06e425154234046ed779dc72dd449c178ac

@nigoroll , do you want a PR for this?

[nigoroll]

@gquintard helpful PRs are always welcome.