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/gtk1/dnd.cpp

@@ -60,7 +60,7 @@ static const wxChar *TRACE_DND = _T("dnd");
 //----------------------------------------------------------------------------
 
 /* XPM */
-static char * page_xpm[] = {
+static const char * page_xpm[] = {
 /* width height ncolors chars_per_pixel */
 "32 32 5 1",
 /* colors */