Add --test_env=JAVA_HOME to Bazel's tests on Windows. (#229)

diff --git a/buildkite/pipelines/bazel-postsubmit.yml b/buildkite/pipelines/bazel-postsubmit.yml
index 5559553..9e4976e 100644
--- a/buildkite/pipelines/bazel-postsubmit.yml
+++ b/buildkite/pipelines/bazel-postsubmit.yml
@@ -74,6 +74,7 @@
     - "--copt=-w"
     - "--host_copt=-w"
     - "--test_env=TEMP"
+    - "--test_env=JAVA_HOME"
     - "--test_timeout=900"
     test_targets:
     - "//src:all_windows_tests"