Issue #12098 : Fix a missing import in the unittests.

Lib/test/test_support.py

@@ -1344,6 +1344,7 @@ def py3k_bytes(b):
 def args_from_interpreter_flags():
     """Return a list of command-line arguments reproducing the current
     settings in sys.flags."""
+    import subprocess
     return subprocess._args_from_interpreter_flags()
 
 def strip_python_stderr(stderr):