bench: Add benchmark for mprotect and fix mmap

[chfast]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 19 lines in your changes missing coverage. Please review.

Project coverage is 94.19%. Comparing base (94582ff) to head (bbae052).

Files with missing lines	Patch %	Lines
test/internal_benchmarks/memory_allocation.cpp	0.00%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1082      +/-   ##
==========================================
- Coverage   94.29%   94.19%   -0.10%     
==========================================
  Files         157      157              
  Lines       17080    17098      +18     
==========================================
  Hits        16105    16105              
- Misses        975      993      +18     

Flag	Coverage Δ
eof_execution_spec_tests	23.50% <0.00%> (-0.03%)	⬇️
ethereum_tests	26.46% <0.00%> (-0.03%)	⬇️
ethereum_tests_silkpre	19.07% <0.00%> (-0.03%)	⬇️
execution_spec_tests	20.20% <0.00%> (-0.03%)	⬇️
unittests	89.26% <0.00%> (-0.10%)	⬇️

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Files with missing lines	Coverage Δ
test/internal_benchmarks/memory_allocation.cpp	0.00% <0.00%> (ø)