vim-patch:8.2.4644: redrawing too often when 'relativenumber' is set (#17756)

Problem:  Redrawing too often when 'relativenumber' is set.
Solution: Only redraw when the cursor line changed. (Lewis Russell,
          closes vim/vim#10040)
1624639ec8

src/nvim/change.c

@@ -287,7 +287,7 @@ static void changed_common(linenr_T lnum, colnr_T col, linenr_T lnume, long xtra
       }
 
       // Relative numbering may require updating more.
-      if (wp->w_p_rnu) {
+      if (wp->w_p_rnu && xtra != 0) {
         redraw_later(wp, SOME_VALID);
       }