services/posixfs: Fix std{in/out} support for Stat

[Xuanwo]

No description provided.

[codecov]

Codecov Report

Merging #35 into master will increase coverage by 0.16%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #35      +/-   ##
==========================================
+ Coverage   77.83%   77.99%   +0.16%     
==========================================
  Files           9        9              
  Lines         961      968       +7     
==========================================
+ Hits          748      755       +7     
  Misses        138      138              
  Partials       75       75

Impacted Files	Coverage Δ
services/posixfs/storager.go	92.63% <100%> (+0.33%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d8bbfdb...25eae56. Read the comment docs.