fixes for the compilation warnings with Sun CC:

1. some fixes for "String literal to char * conversion" warnings (many
   more left in the *.xpm files)
2. fixes for "assignment of function to extern "C" function"
3. a few other miscellaneous ones


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@13478 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/socket.cpp

@@ -862,9 +862,10 @@ char *wxSocketBase::CallbackData(char *data)
 // decoupled from wx_socket_callback and thus they suffer from a variety
 // of problems. Avoid them where possible and use events instead.
 
-static void LINKAGEMODE wx_socket_callback(GSocket * WXUNUSED(socket),
-                                           GSocketEvent notification,
-                                           char *cdata)
+extern "C"
+void LINKAGEMODE wx_socket_callback(GSocket * WXUNUSED(socket),
+                                    GSocketEvent notification,
+                                    char *cdata)
 {
   wxSocketBase *sckobj = (wxSocketBase *)cdata;