bpo-39353: Deprecate the binhex module (GH-18025)

Deprecate binhex4 and hexbin4 standards. Deprecate the binhex module
and the following binascii functions:

* b2a_hqx(), a2b_hqx()
* rlecode_hqx(), rledecode_hqx()
* crc_hqx()
diff --git a/Lib/test/test_binhex.py b/Lib/test/test_binhex.py
index 2f3d53a..86ca37c 100644
--- a/Lib/test/test_binhex.py
+++ b/Lib/test/test_binhex.py
@@ -3,10 +3,12 @@
    Uses the mechanism of the python binhex module
    Based on an original test by Roger E. Masse.
 """
-import binhex
 import unittest
 from test import support
 
+with support.check_warnings(('', DeprecationWarning)):
+    import binhex
+
 
 class BinHexTestCase(unittest.TestCase):