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/IconWindow.c

@@ -56,8 +56,10 @@
 
 #include <Xm/Xm.h>
 #include <Xm/XmP.h>
+#include <Xm/DrawP.h>
 #include <Xm/TextF.h>
 #include <Xm/VirtKeys.h>
+#include <Xm/ScrollBar.h>
 
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -80,6 +82,7 @@
 #include "Prefs.h"
 #include "Common.h"
 #include "Filter.h"
+#include "SharedProcs.h"
 
                            /* For HightlightBorder & UnhighlightBorder */
 externalref XmPrimitiveClassRec xmPrimitiveClassRec;