patch 7.4.992

Problem:    Makefiles for MS-Windows in src/po are outdated.
Solution:   Make them work. (Ken Takata, Taro Muraoka)

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    992,
 /**/
     991,
 /**/