Add some missing private assignment operators

This is needed as part of fixing #1636 as a new version of SIP is required,
which makes these changes necessary.

(cherry picked from commit 676b95ad17)

etg/filesys.py

@@ -40,6 +40,7 @@ def run():
     c = module.find('wxFileSystem')
     assert isinstance(c, etgtools.ClassDef)
     c.addPrivateCopyCtor()
+    c.addPrivateAssignOp()
     c.find('AddHandler.handler').transfer = True
     c.find('RemoveHandler').transferBack = True
 

etg/grid.py

@@ -183,6 +183,7 @@ def run():
     #-----------------------------------------------------------------
     c = module.find('wxGridBlocks')
     c.addPrivateDefaultCtor()
+    c.addPrivateAssignOp()
 
     c.addPyMethod('__iter__', '(self)',
                   'return PyGridBlocksIterator(self)',

etg/renderer.py

@@ -74,6 +74,12 @@ def run():
     c.addPrivateCopyCtor()
     _addDrawTitleBarBitmap(c, False, draw_tb_bmp_doc)
 
+    c = module.find('wxSplitterRenderParams')
+    c.addPrivateAssignOp()
+
+    c = module.find('wxRendererVersion')
+    c.addPrivateAssignOp()
+
     #-----------------------------------------------------------------
     tools.doCommonTweaks(module)
     tools.runGenerators(module)