fstests: Don't use gawk's strtonum

It's a gawk extension and not needed. Make tests pass with non-gawk.

Signed-off-by: Kusanagi Kouichi <slash@ac.auone-net.jp>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

common/filter

@@ -241,9 +241,9 @@ _filter_xfs_io_units_modified()
 		/wrote/ {
 			split($2, bytes, "/")
 
-			bytes_written = strtonum(bytes[1])
+			bytes_written = bytes[1]
 
-			offset = strtonum($NF)
+			offset = $NF
 
 			unit_start = offset / unit_size
 			unit_start = int(unit_start)
@@ -487,14 +487,16 @@ _filter_busy_mount()
 _filter_od()
 {
 	BLOCK_SIZE=$(_get_block_size $SCRATCH_MNT)
-	$AWK_PROG -v block_size=$BLOCK_SIZE '
-		/^[0-9]+/ {
-			offset = strtonum("0"$1);
-			$1 = sprintf("%o", offset / block_size);
-			print $0;
-		}
-		/\*/
-	'
+	while read line; do
+		if test "$line" = '*'
+		then
+			printf '*\n'
+			continue
+		fi
+
+		offset="${line%% *}"
+		printf '%o%s\n' $((offset / BLOCK_SIZE)) "${line#$offset}"
+	done
 }
 
 # Remove quotes from failed mknod calls. Starting with Coreutils v8.25,