Adapt test_bytes for a build --without-doc-strings.
diff --git a/Lib/test/support.py b/Lib/test/support.py
index 1e3aef0..d44436b 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -590,6 +590,10 @@
 
 requires_lzma = unittest.skipUnless(lzma, 'requires lzma')
 
+requires_docstrings = unittest.skipUnless(
+    sysconfig.get_config_var('WITH_DOC_STRINGS'),
+    "test requires docstrings")
+
 is_jython = sys.platform.startswith('java')
 
 # Filename used for testing