preparations for making 'closure' the default calling convention for proc types

lib/wrappers/gtk/atk.nim

@@ -419,7 +419,7 @@ type
     pad32*: TFunction
 
   TEventListener* = proc (para1: PObject){.cdecl.}
-  TEventListenerInitProc* = proc ()
+  TEventListenerInitProc* = proc (){.cdecl.}
   TEventListenerInit* = proc (para1: TEventListenerInitProc){.cdecl.}
   PKeyEventStruct* = ptr TKeyEventStruct
   TKeyEventStruct*{.final, pure.} = object 

lib/wrappers/gtk/gdk2.nim

@@ -291,7 +291,7 @@ type
   PEvent* = ptr TEvent
   TEventFunc* = proc (event: PEvent, data: gpointer){.cdecl.}
   PXEvent* = ptr TXEvent
-  TXEvent* = proc ()
+  TXEvent* = proc () {.cdecl.}
   PFilterReturn* = ptr TFilterReturn
   TFilterReturn* = enum 
     FILTER_CONTINUE, FILTER_TRANSLATE, FILTER_REMOVE
@@ -775,7 +775,7 @@ type
   PWindowObjectClass* = ptr TWindowObjectClass
   TWindowObjectClass* = object of TDrawableClass
   window_invalidate_maybe_recurse_child_func* = proc (para1: PWindow, 
-      para2: gpointer): gboolean
+      para2: gpointer): gboolean {.cdecl.}
 
 proc TYPE_COLORMAP*(): GType
 proc COLORMAP*(anObject: pointer): PColormap

lib/wrappers/gtk/glib2.nim

@@ -2676,7 +2676,7 @@ when false:
   proc g_critical*(format: cstring){.varargs.}
   proc g_warning*(format: cstring){.varargs.}
 type 
-  TGPrintFunc* = proc (str: cstring)
+  TGPrintFunc* = proc (str: cstring){.cdecl, varargs.}
 
 proc g_set_print_handler*(func: TGPrintFunc): TGPrintFunc{.cdecl, 
     dynlib: gliblib, importc: "g_set_print_handler".}