fsmonitor: don't write out state if identity has changed (issue5581)
Inspired by the dirstate fix in dc7efa2826e4, this should fix any race
conditions with the fsmonitor state changing from underneath.
Since we now grab the wlock for any non-invalidate writes, the only situation
this appears to happen in is with a concurrent invalidation. Test that.
<Include>
<?if $(var.Platform) = "x64" ?>
<?define IsX64 = yes ?>
<?else?>
<?define IsX64 = no ?>
<?endif?>
</Include>