Mount individual subdirs in /opt in bazelci.py.
diff --git a/buildkite/bazelci.py b/buildkite/bazelci.py
index 109334c..3835e48 100755
--- a/buildkite/bazelci.py
+++ b/buildkite/bazelci.py
@@ -2069,7 +2069,8 @@
                     "/etc/group:/etc/group:ro",
                     "/etc/passwd:/etc/passwd:ro",
                     "/etc/shadow:/etc/shadow:ro",
-                    "/opt:/opt:ro",
+                    "/opt/android-ndk-r15c:/opt/android-ndk-r15c:ro",
+                    "/opt/android-sdk-linux:/opt/android-sdk-linux:ro",
                     "/var/lib/buildkite-agent:/var/lib/buildkite-agent",
                     "/var/lib/gitmirrors:/var/lib/gitmirrors:ro",
                     "/var/run/docker.sock:/var/run/docker.sock",