showbase: *Global.py modules should not export 'sys' module

direct/src/showbase/ShowBaseGlobal.py

@@ -47,6 +47,7 @@ if sys.version_info >= (3, 0):
 else:
     import __builtin__ as builtins
 builtins.inspect = inspect
+del sys
 
 # this also appears in AIBaseGlobal
 if (not __debug__) and __dev__:

direct/src/showbase/TkGlobal.py

@@ -12,6 +12,9 @@ else:
 if '_Pmw' in sys.modules:
     sys.modules['_Pmw'].__name__ = '_Pmw'
 
+# Don't export this from the module.
+del sys
+
 # Hack to workaround broken Pmw.NoteBook in Python 3
 def bordercolors(root, colorName):
     lightRGB = []