Allow platform-dependent hashlib exports

Author: JelleZijlstra

stdlib/@tests/stubtest_allowlists/common.txt

@@ -465,6 +465,7 @@ urllib.response.addbase.write  # Methods that come from __getattr__() at runtime
 urllib.response.addbase.writelines  # Methods that come from __getattr__() at runtime
 
 (pydoc.Doc.getdocloc)?  # Runtime default is an installation-specific stdlib path.
+(hashlib.__all__)?  # scrypt depends on how OpenSSL was built.
 
 _?weakref\.CallableProxyType\.__getattr__  # Should have all attributes of proxy
 _?weakref\.(ref|ReferenceType)\.__init__  # C implementation has incorrect signature

stdlib/@tests/stubtest_allowlists/darwin.txt

@@ -45,7 +45,6 @@ tkinter.Tk.deletefilehandler  # Methods that come from __getattr__() at runtime
 
 # These entries looks like a `setup-python` bug:
 (dbm.gnu)?
-(hashlib.__all__)?
 (mmap.mmap.resize)?
 (_?locale.bind_textdomain_codeset)?
 (_?locale.bindtextdomain)?