Centralize catgets() calls through MsgCat

CDE has relied upon catgets() implementations following a relaxed
interpretation of the XPG internationalization standard that ignored
-1, the standard error value returned by catopen, as the catalog
argument. However, this same behavior causes segmentation faults with
the musl C library.

This patch:

- Centralizes (with the exception of ToolTalk) all calls to catopen(),
  catgets(), and catclose() through MsgCat within the DtSvc library.
- Prevents calls to catgets() and catclose() that rely upon
  undefined behavior.
- Eliminates a number of bespoke catgets() wrappers, including multiple
  redundant caching implementations designed to work around a design
  peculiarity in HP/UX.
- Eases building CDE without XPG internationalization support by providing
  the appropriate macros.

cde/include/Dt/DtMsgsP.h

@@ -40,7 +40,7 @@
 #define CONST
 
 #ifdef I18N_MSG
-#include <nl_types.h>
+#include <Dt/MsgCatP.h>
 #define DTWIDGET_GETMESSAGE(set, number, string)\
     (char *) _DtWidgetGetMessage(set, number, string)
 

cde/include/Dt/DtNlUtils.h

@@ -34,13 +34,12 @@
 /**************************************************************************/
 
 #ifdef NLS16
-
 #include <stdlib.h>
 #include <locale.h>
 #include <string.h>
 #include <limits.h>
-#include <nl_types.h>
 #include <langinfo.h>
+#include <Dt/MsgCatP.h>
 #endif
 
 #include <X11/Intrinsic.h>

cde/include/Dt/MsgCatP.h

@@ -44,7 +44,18 @@
 extern "C" {
 #endif
 
-extern char *_DtCatgetsCached(nl_catd catd, int set, int num, char *dflt);
+#define CATOPEN(name,oflag) catopen(name,oflag)
+#define CATCLOSE(catd) _DtCatclose(catd)
+#define CATGETS(catd,set,num,dflt) _DtCatgets(catd,set,num,dflt)
+extern char *_DtCatgets(nl_catd catd, int set, int num, const char *dflt);
+extern int _DtCatclose(nl_catd catd);
+
+#if 0 /* TODO: Decide between !I18N_MSG and NO_MESSAGE_CATALOG */
+typedef int nl_catd;
+#define CATOPEN(name,oflag) 0
+#define CATCLOSE(catd) 0
+#define CATGETS(catd,set,num,dflt) dflt
+#endif
 
 #ifdef __cplusplus
 }

cde/include/Dt/PrintMsgsP.h

@@ -37,7 +37,7 @@
 #define _DtPrintMsgsP_h
 
 #ifdef I18N_MSG
-#include <nl_types.h>
+#include <Dt/MsgCatP.h>
 #define DTPRINT_GETMESSAGE(set, number, string) \
     _DtPrintGetMessage(set, number, string)
 

cde/include/Dt/SearchP.h

@@ -95,7 +95,7 @@
  * Removed debugging #defines.
  */
 #include "Search.h"	/* the "public" header file */
-#include <nl_types.h>	/* for nl_catd below and all cat...() funcs */
+#include <Dt/MsgCatP.h>	/* for nl_catd below and all cat...() funcs */
 #include <sys/types.h>
 #include <netinet/in.h>
 
@@ -600,7 +600,7 @@ extern void swab_objrec (struct or_objrec *rec,  SWABDIR direction);
 
 /*------------------------- MACROS ---------------------------*/
 /* (Use offsetof() in stddef.h to replace my old OFFSET macro) */
-#define NULLORSTR(str)      ((str)?str:catgets(dtsearch_catd,1,1,"<null>"))
+#define NULLORSTR(str)      ((str)?str:CATGETS(dtsearch_catd,1,1,"<null>"))
 #define NUMARRAY(arr)       ((sizeof(arr) / sizeof(arr[0])))
 
 /****************************************/

cde/include/Dt/Setlocale.h

@@ -41,7 +41,7 @@
 
 #include	<locale.h>
 #include	<limits.h>
-#include	<nl_types.h>
+#include	<Dt/MsgCatP.h>
 #include	<langinfo.h>
 #include	<Dt/Collate.h>