fsck: Fix parsing of -r

Fix regression introduced by commit 658c089: -r cannot be used as a last
option:

fsck -r /dev/sda1
fsck: invalid argument -r: '/dev/sda1'

Signed-off-by: Stanislav Brabec <sbrabec@suse.cz>

disk-utils/fsck.c

@@ -1525,7 +1525,7 @@ static void parse_argv(int argc, char *argv[])
 				if (arg[j+1]) {					/* -r<fd> */
 					report_stats_fd = strtou32_or_err(arg+j+1, _("invalid argument -r"));
 					goto next_arg;
-				} else if (i+1 < argc && *argv[i+1] != '-') {	/* -r <fd> */
+				} else if (i+1 < argc && *argv[i+1] >= '0' && *argv[i+1] <= '9') {	/* -r <fd> */
 					report_stats_fd = strtou32_or_err(argv[i+1], _("invalid argument -r"));
 					++i;
 					goto next_arg;