patch 9.1.1680: MS-Windows: possible buffer-under run in if_cscope

Problem:  MS-Windows: possible buffer-under run in if_cscope
          cs_pathcomponents() (Murali Aniruddhan)
Solution: Fix the loop and do not decrement the pointer twice.

closes: #18091

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/if_cscope.c

@@ -1940,12 +1940,18 @@ cs_pathcomponents(char *path)
 
     s = path + strlen(path) - 1;
     for (i = 0; i < p_cspc; ++i)
-	while (s > path && *--s != '/'
+    {
+	while (s > path)
+	{
+	   s--;
+	   if (*s == '/'
 #ifdef MSWIN
-		&& *--s != '\\'
+		|| *s == '\\'
 #endif
 		)
-	    ;
+	      break;
+	}
+    }
     if ((s > path && *s == '/')
 #ifdef MSWIN
 	|| (s > path && *s == '\\')

src/version.c

@@ -724,6 +724,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1680,
 /**/
     1679,
 /**/