remoteexec_info.bzl: Pass REPROXY_CFG_FILE to the build environment

BUG=b:269549907
TEST=CQ

Change-Id: I94b073fb9c3c60c95d163da81529c4faea45e2f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/bazel/+/5371385
Tested-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Ryo Hashimoto <hashimoto@chromium.org>
Reviewed-by: Tim Bain <tbain@google.com>
diff --git a/module_extensions/portage/remoteexec_info.bzl b/module_extensions/portage/remoteexec_info.bzl
index 4fd2471..d45a4d3 100644
--- a/module_extensions/portage/remoteexec_info.bzl
+++ b/module_extensions/portage/remoteexec_info.bzl
@@ -10,6 +10,7 @@
     "GCE_METADATA_HOST",
     "GCE_METADATA_IP",
     "GCE_METADATA_ROOT",
+    "REPROXY_CFG_FILE",
 ]
 
 def _remoteexec_info_repository_impl(repo_ctx):