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/Menu.c

@@ -65,6 +65,7 @@
 
 #include <Xm/XmP.h>
 #include <Xm/CascadeBG.h>
+#include <Xm/TextF.h>
 #include <Xm/PushBG.h>
 #include <Xm/RowColumn.h>
 #include <Xm/SeparatoG.h>
@@ -72,6 +73,8 @@
 #include <Xm/MessageB.h>
 #include <Xm/MenuShellP.h>
 
+#include <Xm/XmPrivate.h> /* _XmGetActiveTopLevelMenu */
+
 #include <X11/ShellP.h>
 
 #include <Dt/DtP.h>
@@ -81,6 +84,7 @@
 #include <Dt/Connect.h>
 #include <Dt/Indicator.h>
 #include <Dt/FileM.h>
+#include <Dt/SharedProcs.h>
 
 #include "Encaps.h"
 #include "SharedProcs.h"