Work around pip 25/pyproject_hooks 1.2.0 path meddling

pip 25/pyproject_hooks 1.2.0 inserts `_BackendPathFinder` into
`sys.meta_path` at index 0, and that makes the import machinery find the
directory `platform` as a namespace instead of importing the standrd
platform module.

Work around by removing this finder from `sys.meta_path` if it is
present at index 0.

Upstream bug: pypa/pip#13289

Author: mjg

setup.py

@@ -33,11 +33,15 @@
         run swig.
 '''
 
+# Work around pip 25/pyproject_hooks 1.2.0 path meddling:
+import sys
+if sys.meta_path[0].__class__.__name__ == '_BackendPathFinder':
+    sys.meta_path.pop(0)
+
 import os
 import platform
 import re
 import subprocess
-import sys
 import time