hashlib: Rename submodules to avoid naming conflicts.

Both submodules and classes are named like "sha256", this may lead to
issues when loading just specific items from modules.

hashlib/hashlib/__init__.py

@@ -1,2 +1,2 @@
-from .sha256 import sha224, sha256
-from .sha512 import sha384, sha512
+from ._sha256 import sha224, sha256
+from ._sha512 import sha384, sha512

hashlib/hashlib/_sha224.py

@@ -0,0 +1 @@
+from ._sha256 import sha224

hashlib/hashlib/_sha384.py

@@ -0,0 +1 @@
+from ._sha512 import sha384

hashlib/hashlib/sha224.py

@@ -1 +0,0 @@
-from .sha256 import sha224

hashlib/hashlib/sha384.py

@@ -1 +0,0 @@
-from .sha512 import sha384

hashlib/test_hashlib.py

@@ -1,5 +1,5 @@
-from hashlib.sha256 import test as sha256_test
-from hashlib.sha512 import test as sha512_test
+from hashlib._sha256 import test as sha256_test
+from hashlib._sha512 import test as sha512_test
 
 
 sha256_test()