patch 8.2.2547: "%" command not accurate for big files

Problem:    "%" command not accurate for big files.
Solution:   Make it more accurate for files up to 21M lines. (Dominique Pellé,
            closes #7889)

Author: brammool

src/normal.c

@@ -4769,9 +4769,11 @@ nv_percent(cmdarg_T *cap)
 	{
 	    cap->oap->motion_type = MLINE;
 	    setpcmark();
-	    // Round up, so CTRL-G will give same value.  Watch out for a
-	    // large line count, the line number must not go negative!
-	    if (curbuf->b_ml.ml_line_count > 1000000)
+	    // Round up, so 'normal 100%' always jumps at the line line.
+	    // Beyond 21474836 lines, (ml_line_count * 100 + 99) would
+	    // overflow on 32-bits, so use a formula with less accuracy
+	    // to avoid overflows.
+	    if (curbuf->b_ml.ml_line_count >= 21474836)
 		curwin->w_cursor.lnum = (curbuf->b_ml.ml_line_count + 99L)
 							 / 100L * cap->count0;
 	    else

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2547,
 /**/
     2546,
 /**/