patch 8.1.1606: on a narrow screen ":hi" output is confusing

Problem:    On a narrow screen ":hi" output is confusing.
Solution:   Insert a space between highlight group name and "xxx". (Masato
            Nishihaga, closes #4599)
diff --git a/src/syntax.c b/src/syntax.c
index 8c23d20..4d42346 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -9440,6 +9440,7 @@
 {
     int	    endcol = 19;
     int	    newline = TRUE;
+    int	    name_col = 0;
 
     if (!did_header)
     {
@@ -9447,6 +9448,7 @@
 	if (got_int)
 	    return TRUE;
 	msg_outtrans(HL_TABLE()[id - 1].sg_name);
+	name_col = msg_col;
 	endcol = 15;
     }
     else if (msg_col + outlen + 1 >= Columns)
@@ -9471,6 +9473,8 @@
     /* Show "xxx" with the attributes. */
     if (!did_header)
     {
+	if (endcol == Columns - 1 && endcol <= name_col)
+	    msg_putchar(' ');
 	msg_puts_attr("xxx", syn_id2attr(id));
 	msg_putchar(' ');
     }