progress bar: round to the nearest instead of truncating down

Often the throughput output is requested when the data read so far is
one smaller than multiple of 1024; because 1023/1024 is ~0.999, it often
shows up as 0.99 because the code currently truncates.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

progress.c

@@ -121,13 +121,13 @@ static void throughput_string(struct throughput *tp, off_t total,
 			      (int)(total >> 30),
 			      (int)(total & ((1 << 30) - 1)) / 10737419);
 	} else if (total > 1 << 20) {
+		int x = total + 5243;  /* for rounding */
 		l -= snprintf(tp->display, l, ", %u.%2.2u MiB",
-			      (int)(total >> 20),
-			      ((int)(total & ((1 << 20) - 1)) * 100) >> 20);
+			      x >> 20, ((x & ((1 << 20) - 1)) * 100) >> 20);
 	} else if (total > 1 << 10) {
+		int x = total + 5;  /* for rounding */
 		l -= snprintf(tp->display, l, ", %u.%2.2u KiB",
-			      (int)(total >> 10),
-			      ((int)(total & ((1 << 10) - 1)) * 100) >> 10);
+			      x >> 10, ((x & ((1 << 10) - 1)) * 100) >> 10);
 	} else {
 		l -= snprintf(tp->display, l, ", %u bytes", (int)total);
 	}