Bug 1381526: switch OSX DE builds to cross-compile r=kmoir

MozReview-Commit-ID: 3MyVvaYRbJ4

--HG--
extra : rebase_source : 51d16c4b6fb9508c2e7c55e5ce87a1badd1fe00a

taskcluster/ci/build/macosx.yml

@@ -76,16 +76,19 @@ macosx64-devedition/opt:
         product: devedition
         job-name: macosx64-devedition-opt
     treeherder:
-        platform: macosx64-devedition/opt
+        platform: osx-cross-devedition/opt
         symbol: tc(B)
         tier: 1
-    worker-type: buildbot-bridge/buildbot-bridge
+    worker-type: aws-provisioner-v1/gecko-{level}-b-macosx64
+    worker:
+        max-run-time: 36000
+        env:
+            TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/macosx64/cross-releng.manifest"
     run:
         using: mozharness
         actions: [get-secrets build update]
         config:
-            - builds/releng_base_mac_64_builds.py
-            - balrog/production.py
+            - builds/releng_base_mac_64_cross_builds.py
         script: "mozharness/scripts/fx_desktop_build.py"
         secrets: true
         tooltool-downloads: internal