patch 8.2.1558: signs test fails

Problem:    Signs test fails.
Solution:   Add missing change to sign.c.

src/sign.c

@@ -517,6 +517,7 @@ buf_get_signattrs(win_T *wp, linenr_T lnum, sign_attrs_T *sattr)
 		sattr->sat_texthl = syn_id2attr(sp->sn_text_hl);
 	    if (sp->sn_line_hl > 0)
 		sattr->sat_linehl = syn_id2attr(sp->sn_line_hl);
+	    sattr->sat_priority = sign->se_priority;
 
 	    // If there is another sign next with the same priority, may
 	    // combine the text and the line highlighting.

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1558,
 /**/
     1557,
 /**/