fix: integer overflow in Complexity analysis

[quentin]

Avoid overflow by saturation of complexity.

fixes #2508

[codecov]

Codecov Report

Attention: Patch coverage is 93.75000% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.10%. Comparing base (e6cc668) to head (74ba385).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/ram/analysis/Complexity.cpp	93.75%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2509      +/-   ##
==========================================
+ Coverage   81.05%   81.10%   +0.04%     
==========================================
  Files         492      492              
  Lines       30922    30934      +12     
==========================================
+ Hits        25065    25090      +25     
+ Misses       5857     5844      -13     

Files with missing lines	Coverage Δ
src/ram/analysis/Complexity.cpp	97.36% <93.75%> (-2.64%)	⬇️

... and 4 files with indirect coverage changes