Utils: Add python2 cp65001 compat

git-bash ptty on Windows uses cp65001 by default. Attempting to
decode this codepage in cpython < 3.3 will fail as the encoding
is unsupported. cp65001 is an alias for utf8 on Windows and is
implemented as such since cpython > 3.8. Use this to provide
minimal compatibility for cp65001 to waf running under python2.

waflib/Utils.py

@@ -452,6 +452,8 @@ def console_encoding():
 			pass
 		else:
 			if codepage:
+				if 65001 == codepage and sys.version_info < (3, 3):
+					return 'utf-8'
 				return 'cp%d' % codepage
 	return sys.stdout.encoding or ('cp1252' if is_win32 else 'latin-1')