Fixed compile warning due to default cast

[fawdlstty]

Fixed compile warning due to default cast

[tencent-adm]

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[codecov-io]

Codecov Report

Merging #2201 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2201   +/-   ##
=======================================
  Coverage   86.47%   86.47%           
=======================================
  Files         511      511           
  Lines       83223    83223           
=======================================
  Hits        71971    71971           
  Misses      11252    11252           

Impacted Files	Coverage Δ
src/layer/roialign.cpp	92.79% <100.00%> (ø)
src/layer/x86/roialign_x86.cpp	87.07% <100.00%> (ø)
src/mat_pixel_affine.cpp	96.33% <100.00%> (ø)

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[lgtm-com]

This pull request fixes 2 alerts when merging 195a4dd into bc24712 - view on LGTM.com

fixed alerts:

• 2 for Declaration hides parameter

[nihui]

Thanks for your contribution !

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.47%. Comparing base (bc24712) to head (195a4dd).
Report is 1649 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2201   +/-   ##
=======================================
  Coverage   86.47%   86.47%           
=======================================
  Files         511      511           
  Lines       83223    83223           
=======================================
  Hits        71971    71971           
  Misses      11252    11252           

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