SF patch 661583: Remove old code from lib\os.py

A patch from Andrew Wilkinson to change some bizarre old exec statements
specific to NT and CE.

Lib/os.py

@@ -61,9 +61,8 @@ elif 'nt' in _names:
     curdir = '.'; pardir = '..'; sep = '\\'; pathsep = ';'
     defpath = '.;C:\\bin'
     from nt import *
-    for i in ['_exit']:
     try:
-            exec "from nt import " + i
+        from nt import _exit
     except ImportError:
         pass
     import ntpath
@@ -127,9 +126,8 @@ elif 'ce' in _names:
     curdir = '.'; pardir = '..'; sep = '\\'; pathsep = ';'
     defpath = '\\Windows'
     from ce import *
-    for i in ['_exit']:
     try:
-            exec "from ce import " + i
+        from ce import _exit
     except ImportError:
         pass
     # We can use the standard Windows path.