Fix 'cannot seek vector iterator' in debug windows build

[antoszy]

Motivation

Fixes: #1537

Modification

Adding nbInputs to the mFeatmapStrides.begin() iterator cases it to go out of range of the mFeatmapStrides vector. When this is compiled in debug build in MS compiler, it causes an exception. If we decrement the value first and then add it to iterator, than the iterator stays in correct vector range.

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit tests to ensure the correctness.
3. If the modification has a dependency on downstream projects of a newer version, this PR should be tested with all supported versions of downstream projects.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[CLAassistant]

All committers have signed the CLA.

[lvhan028]

LGTM

[lvhan028]

@antoszy could you also open a PR to master branch?

[openmmlab-bot]

antoszy ，您好！您在MMDeploy项目中给我们提的PR非常重要，感谢您付出私人时间帮助改进开源项目，相信很多开发者会从你的PR中受益。
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Dear antoszy ,
First of all, we want to express our gratitude for your significant PR in the MMDeploy project. Your contribution is highly appreciated, and we are grateful for your efforts in helping improve this open-source project during your personal time. We believe that many developers will benefit from your PR.
We are looking forward to continuing our collaboration with you. OpenMMLab has established a special contributors' organization called MMSIG, which provides contributors with open-source certificates, a recognition system, and exclusive rewards. You can contact us by adding our WeChat（if you have WeChat): openmmlabwx, or join in our discord：https://discord.gg/raweFPmdzG. We sincerely hope you will join us!
Best regards！ @antoszy