[libc++] Add new queues for specific macOS system versions

This will allow running back-deployment testing on macOS only on systems
running the right version of macOS. For the time being, we're cheating
because we don't have actual machines running older than 10.15.

GitOrigin-RevId: 3fb83853791cabd08fbc6cd35ed2b82c0ffcc2d6
diff --git a/utils/ci/buildkite-pipeline.yml b/utils/ci/buildkite-pipeline.yml
index f133a04..b149a14 100644
--- a/utils/ci/buildkite-pipeline.yml
+++ b/utils/ci/buildkite-pipeline.yml
@@ -214,7 +214,7 @@
       - "**/test-results.xml"
       - "**/*.abilist"
     agents:
-      queue: "libcxx-macos-builders"
+      queue: "libcxx-builders-macos"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
@@ -270,7 +270,7 @@
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-macos-builders"
+      queue: "libcxx-builders-macos"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
@@ -281,7 +281,7 @@
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-macos-builders"
+      queue: "libcxx-builders-macos"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
@@ -293,7 +293,7 @@
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-macos-builders"
+      queue: "libcxx-builders-macos10.15" # TODO: For now, we're running the back-deployment tests for 10.9 on 10.15, because we don't have proper 10.9 machines
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
@@ -304,7 +304,7 @@
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-macos-builders"
+      queue: "libcxx-builders-macos10.15"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
diff --git a/utils/ci/macos-ci-setup b/utils/ci/macos-ci-setup
index 97d814c..f59f50d 100755
--- a/utils/ci/macos-ci-setup
+++ b/utils/ci/macos-ci-setup
@@ -14,8 +14,10 @@
 
 CFG_DIR="$(brew --prefix)/etc/buildkite-agent"
 
+version="$(sw_vers -productVersion | sed -E 's/([0-9]+).([0-9]+).[0-9]+/\1.\2/')"
+
 # Setup the tags of the agent
-echo 'tags="queue=libcxx-macos-builders"' >> "${CFG_DIR}/buildkite-agent.cfg"
+echo 'tags="queue=libcxx-builders-macos,queue=libcxx-builders-macos${version}"' >> "${CFG_DIR}/buildkite-agent.cfg"
 
 # Setup the BuildKite Agent token
 sed -i '' "s/xxx/${BUILDKITE_AGENT_TOKEN}/g" "${CFG_DIR}/buildkite-agent.cfg"