cmd/upspinfs: reduce kernel caching time for stat info
cmd/upspinfs: reduce kernel caching time for stat info

Change-Id: Id4299e6360fc85661530af90389706f5bedc83a3
Reviewed-on: https://upspin-review.googlesource.com/16420
Reviewed-by: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>
Reviewed-by: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

upspin/upspin,upspin/upspin