dtfile: Add missing prototypes

Add missing prototypes and header files to the dtfile
code in order to move closer towards 64-bit compatibility.

Extract the following functions from Motif internal headers:

_XmGetWidgetExtData
_XmRecordEvent
_XmStringUngenerate
_XmTextFieldSetDestination
_XmGetActiveTopLevelMenu

Extract manually prototypes of the obsolete Motif interface:
_XmHighlightBorder
_XmUnhighlightBorder

Remove XmPrivate.h if extractprototype.awk fails

Make the following header files available via -I:
	codelibs/boolean.h
	codelibs/pathutils.h
	codelibs/shellutils.h
and remove shellutils.h from dtwm directory.

cde/programs/dtfile/Encaps.h

@@ -332,6 +332,10 @@ extern void _DtShowBuiltDialog(
                         Boolean iconify_state,
                         XClassHint * classHints ) ;
 
+extern void _DtChangeTo(
+                        XtPointer client_data,
+                        char  *directory) ;
+
 extern void _DtFreeDialog(
                         DialogData *dialog_data);
 /********    End Public Function Declarations    ********/