Fix LE/BE_INT() and BYTE_SWAP_INT() for 64-bit long targets (Linux-x64)

long is 64-bits (8 bytes), not 32-bit on some target platforms (e.g. Linux-x64), so don't assume sizeof(long)==4.

It appears we weren't using these "automatic" integer-size macros anywhere that I can see, so no harm, but might as well fix them.

Also remove BYTE_SWAP_SHORT and BYTE_SWAP_LONG since they're terribly named. Retain the LE/BE_SHORT/LONG macros since we're using them currently in SBBS (e.g. js_file.c).

src/xpdev/xpendian.h

-/* xpendian.h */
-
 /* Macros to convert integer "endianness" */
 
-/* $Id: xpendian.h,v 1.6 2018/07/24 01:13:10 rswindell Exp $ */
-
 /****************************************************************************
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@@ -15,41 +11,27 @@
  * as published by the Free Software Foundation; either version 2			*
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  * See the GNU Lesser General Public License for more details: lgpl.txt or	*
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+ * https://www.gnu.org/licenses/old-licenses/lgpl-2.0.html					*
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 #ifndef _XPENDIAN_H
 #define _XPENDIAN_H
 
+#include "gen_defs.h"
+
 /************************/
 /* byte-swapping macros */
 /************************/
-#define BYTE_SWAP_16(x)	((((short)(x)&0xff00)>>8) | (((short)(x)&0x00ff)<<8))
-#define BYTE_SWAP_32(x)	((((long)(x)&0xff000000)>>24) | (((long)(x)&0x00ff0000)>>8) | (((long)(x)&0x0000ff00)<<8) | (((long)(x)&0x000000ff)<<24))
-
-/* these may need to be updated for > 32-bit platforms */
-#define BYTE_SWAP_SHORT(x)	BYTE_SWAP_16(x)
-#define BYTE_SWAP_LONG(x)	BYTE_SWAP_32(x)
+#define BYTE_SWAP_16(x)	((((WORD)(x)&0xff00)>>8) | (((WORD)(x)&0x00ff)<<8))
+#define BYTE_SWAP_32(x)	((((DWORD)(x)&0xff000000)>>24) | (((DWORD)(x)&0x00ff0000)>>8) | (((DWORD)(x)&0x0000ff00)<<8) | (((DWORD)(x)&0x000000ff)<<24))
 
 /* auto-detect integer size */
-#define BYTE_SWAP_INT(x)	(sizeof(x)==sizeof(short) ? BYTE_SWAP_SHORT(x) : sizeof(x)==sizeof(long) ? BYTE_SWAP_LONG(x) : (x))
+#define BYTE_SWAP_INT(x)	(sizeof(x)==2 ? BYTE_SWAP_16(x) : sizeof(x)==4 ? BYTE_SWAP_32(x) : (x))
 
 /********************************/
 /* Architecture-specific macros */
@@ -61,8 +43,8 @@
 	#define BE_INT16(x)		(x)
 	#define BE_INT32(x)		(x)
 	#define BE_INT(x)		(x)
-	#define LE_SHORT(x)		BYTE_SWAP_SHORT(x)
-	#define LE_LONG(x)		BYTE_SWAP_LONG(x)
+	#define LE_SHORT(x)		BYTE_SWAP_16(x)
+	#define LE_LONG(x)		BYTE_SWAP_32(x)
 	#define LE_INT16(x)		BYTE_SWAP_16(x)
 	#define LE_INT32(x)		BYTE_SWAP_32(x)
 	#define LE_INT(x)		BYTE_SWAP_INT(x)
@@ -74,8 +56,8 @@
 	#define LE_INT16(x)		(x)
 	#define LE_INT32(x)		(x)
 	#define LE_INT(x)		(x)
-	#define BE_SHORT(x)		BYTE_SWAP_SHORT(x)
-	#define BE_LONG(x)		BYTE_SWAP_LONG(x)
+	#define BE_SHORT(x)		BYTE_SWAP_16(x)
+	#define BE_LONG(x)		BYTE_SWAP_32(x)
 	#define BE_INT16(x)		BYTE_SWAP_16(x)
 	#define BE_INT32(x)		BYTE_SWAP_32(x)
 	#define BE_INT(x)		BYTE_SWAP_INT(x)