Problem: no overflow check when add gasLimit to gasWanted

[mmsqe]

Closes: #XXX

Description

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For contributor use:

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

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For admin use:

• Added appropriate labels to PR (ex. WIP, R4R, docs, etc)
• Reviewers assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 61.55%. Comparing base (9c959a2) to head (c1af761).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #500      +/-   ##
===========================================
+ Coverage    61.53%   61.55%   +0.01%     
===========================================
  Files          128      128              
  Lines         9495     9496       +1     
===========================================
+ Hits          5843     5845       +2     
  Misses        3111     3111              
+ Partials       541      540       -1     

Files	Coverage Δ
app/ante/eth.go	78.68% <75.00%> (+1.00%)	⬆️