Add stub for standard library crypt module (#1641)

stdlib/2and3/crypt.pyi

@@ -0,0 +1,18 @@
+import sys
+from typing import List, NamedTuple, Optional, Union
+
+
+if sys.version_info >= (3, 3):
+    class _Method: ...
+
+    METHOD_CRYPT: _Method
+    METHOD_MD5: _Method
+    METHOD_SHA256: _Method
+    METHOD_SHA512: _Method
+
+    methods: List[_Method]
+
+    def mksalt(method: Optional[_Method] = ...) -> str: ...
+    def crypt(word: str, salt: Optional[Union[str, _Method]] = ...) -> str: ...
+else:
+    def crypt(word: str, salt: str) -> str: ...