Back out "get rid of bundled init_cinderx"

Summary:
Original commit changeset: fe566e19e32c

Original Phabricator Diff: D70263853

Multisect failure: T216700091

Hand to manually backout because of bouncy castle failure: https://www.internalfb.com/sandcastle/group/nonce/6964058095711753/

Reviewed By: alexmalyshev

Differential Revision: D70920235

fbshipit-source-id: 11c4d5dec7c367f2b696b814bc1c2d8f2554f6d8

Author: pilleye

Lib/init_cinderx.py

@@ -0,0 +1,22 @@
+# ONLY USED FOR CINDERX DEVELOPMENT
+# This file is deliberately not included in the set of deep-frozen bootstrap
+# libraries so it can easily be excluded from the distribution to avoid
+# attempting to initialize CinderX. This is desirable because this code imports
+# importlib.util and some tests are surprised when they find this unexpectedly
+# loaded as part of bootstrap.
+
+import importlib.util
+
+# `cinderx` is the Python module in fbcode/cinderx/PythonLib which wraps the
+# `_cinderx` C++ extension in fbcode/cinderx/_cinderx.cpp.  Both need to be
+# available to load CinderX.
+if not (
+    importlib.util.find_spec("cinderx") is None
+    or importlib.util.find_spec("_cinderx") is None
+):
+    try:
+        import cinderx
+
+        cinderx.init()
+    except Exception as e:
+        raise RuntimeError("Failed to initialize CinderX module") from e