util: drop statmtimesec We've globablly forced stat to return integer times which agrees with our extension code, so this is no longer needed. This speeds up status on mozilla-central substantially: $ hg perfstatus ! wall 0.190179 comb 0.180000 user 0.120000 sys 0.060000 (best of 53) $ hg perfstatus ! wall 0.275729 comb 0.270000 user 0.210000 sys 0.060000 (best of 36)