Migrate definitions of several platform-dependent path-related variables

into the relevant path modules.  See patch #686397.

Lib/ntpath.py

@@ -13,8 +13,24 @@ __all__ = ["normcase","isabs","join","splitdrive","split","splitext",
            "basename","dirname","commonprefix","getsize","getmtime",
            "getatime","getctime", "islink","exists","isdir","isfile","ismount",
            "walk","expanduser","expandvars","normpath","abspath","splitunc",
+           "curdir","pardir","sep","pathsep","defpath","altsep","extsep",
            "realpath","supports_unicode_filenames"]
 
+# strings representing various path-related bits and pieces
+curdir = '.'
+pardir = '..'
+extsep = '.'
+sep = '\\'
+pathsep = ';'
+altsep = None
+if 'ce' in sys.builtin_module_names:
+    defpath = '\\Windows'
+elif 'os2' in sys.builtin_module_names:
+    # OS/2 w/ EMX
+    altsep = '/'
+else:
+    defpath = '.;C:\\bin'
+
 # Normalize the case of a pathname and map slashes to backslashes.
 # Other normalizations (such as optimizing '../' away) are not done
 # (this is done by normpath).