actix-utils: Remove unsound custom Cell as well

[JohnTitor]

PR Type

Bug Fix/Refactor

PR Checklist

Check your PR fulfills the following:

• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.
• A changelog entry has been made for the appropriate packages.

Overview

The changes are the almost same as #158, but it's for actix-utils.
Fixes #160
cc @Shnatsel

[codecov]

Codecov Report

Merging #161 into master will decrease coverage by 0.02%.
The diff coverage is 96.61%.

@@            Coverage Diff             @@
##           master     #161      +/-   ##
==========================================
- Coverage   60.50%   60.47%   -0.03%     
==========================================
  Files          74       73       -1     
  Lines        4790     4782       -8     
==========================================
- Hits         2898     2892       -6     
+ Misses       1892     1890       -2     

Impacted Files	Coverage Δ
actix-utils/src/either.rs	0.00% <ø> (ø)
actix-utils/src/stream.rs	0.00% <ø> (ø)
actix-utils/src/time.rs	80.00% <83.33%> (ø)
actix-utils/src/condition.rs	93.61% <100.00%> (+0.13%)	⬆️
actix-utils/src/mpsc.rs	76.31% <100.00%> (+0.31%)	⬆️
actix-utils/src/oneshot.rs	94.87% <100.00%> (+0.18%)	⬆️

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[Shnatsel]

Looks good to me on the surface. I can't claim to understand that's going on, though.

Thanks for the swift fix!

[cetra3]

Looks good to me!

[robjtede]

nice job, we should follow up soon and get all the unsafe blocks documented and debug_assert-ed