https://github.com/mchehab/zbar/pull/329, plus pull in stddef.h

Index: zbar/img_scanner.c
--- zbar/img_scanner.c.orig
+++ zbar/img_scanner.c
@@ -33,6 +33,7 @@
 #endif

 #include <assert.h>
+#include <stddef.h> /* ptrdiff_t */
 #include <stdlib.h> /* malloc, free */
 #include <string.h> /* memcmp, memset, memcpy */

@@ -862,7 +863,7 @@ static void zbar_send_code_via_dbus(zbar_image_scanner
     do {                                 \
 	x += (dx);                       \
 	y += (dy);                       \
-	p += (dx) + ((uintptr_t)(dy)*w); \
+	p += (ptrdiff_t)(dx) + (intptr_t)(dy) * (intptr_t)w; \
     } while (0);

 static void *_zbar_scan_image(zbar_image_scanner_t *iscn, zbar_image_t *img)
