patch 9.2.0258: memory leak in add_mark()

Problem:  memory leak in add_mark()
Solution: Free lpos in the error case when it hasn't been added to the
          dict yet (Huihui Huang)

closes: #19827

Signed-off-by: Huihui Huang <625173@qq.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: huanghuihui0904

src/mark.c

@@ -1484,7 +1484,11 @@ add_mark(list_T *l, char_u *mname, pos_T *pos, int bufnr, char_u *fname)
     if (dict_add_string(d, "mark", mname) == FAIL
 	    || dict_add_list(d, "pos", lpos) == FAIL
 	    || (fname != NULL && dict_add_string(d, "file", fname) == FAIL))
+    {
+	if (lpos->lv_refcount == 0)
+	    list_free(lpos);
 	return FAIL;
+    }
 
     return OK;
 }

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    258,
 /**/
     257,
 /**/