patch 9.2.0002: str2specialbuf() can be improved

Problem:  str2specialbuf() can be improved
Solution: Optimize str2specialbuf function in message.c
          (Yasuhiro Matsumoto)

closes: #19415

Signed-off-by: Yasuhiro Matsumoto <mattn.jp@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/message.c

@@ -2012,14 +2012,22 @@ str2special(
     void
 str2specialbuf(char_u *sp, char_u *buf, int len)
 {
-    char_u	*s;
+    char_u     *s;
+    size_t     buf_len = 0;
+    size_t     s_len;
 
     *buf = NUL;
     while (*sp)
     {
-	s = str2special(&sp, FALSE, FALSE);
-	if ((int)(STRLEN(s) + STRLEN(buf)) < len)
-	    STRCAT(buf, s);
+        s = str2special(&sp, FALSE, FALSE);
+        s_len = STRLEN(s);
+        if (buf_len + s_len < (size_t)len)
+        {
+            STRCPY(buf + buf_len, s);
+            buf_len += s_len;
+        }
+        else
+            break;
     }
 }
 

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2,
 /**/
     1,
 /**/