Build mesa on amd64 too

Otherwise we fail the patched packages check. We don't build
on armhf since this would just take way too long and we're
not building images for it in Jenkins.

Someone needing that image can adjust the patched list.

jobs.yml

@@ -45,7 +45,7 @@ librem5-devkit-tools:
   branch: master
 mesa:
   url: https://source.puri.sm/Librem5/mesa.git
-  archs: ['aarch64']
+  archs: ['aarch64', 'amd64']
   branch: 'pureos/purple'
 mfgtools:
   url: https://source.puri.sm/Librem5/mfgtools