Fix mirroring for non-platform source-only Python packages

I ran into an issue with gflags where the wheel wasn't getting
mirrored properly. This is the first wheel that we built ourselves
that didn't have any native extensions. I.e. it's a non-platform
wheel. The logic accidentally disregarded them when figuring out which
wheels need to get mirrored.

This patch fixes the error. `gflags` now gets mirrored properly.

Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
Change-Id: I2a06ca6fc2fccaa864693571954771b4ad44b398
diff --git a/tools/python/generate_pip_packages_in_docker.sh b/tools/python/generate_pip_packages_in_docker.sh
index 13d51b7..f651918 100755
--- a/tools/python/generate_pip_packages_in_docker.sh
+++ b/tools/python/generate_pip_packages_in_docker.sh
@@ -115,6 +115,7 @@
   echo "Repairing wheel ${wheel}"
   if ! auditwheel show "${wheel_path}"; then
     echo "Assuming ${wheel} is a non-platform wheel. Skipping."
+    cp "${wheel_path}" "${SCRIPT_DIR}"/wheelhouse/
     continue
   fi
   auditwheel repair \