cannon: Add MTCannon-specific differential tests

[mbaxter]

Description

Add tests to cover new functionality in MTCannon: test new syscalls and thread traversal.

Other changes include:

• Some fixes:
  • Fix FutexWait - don't set thread.FutexAddr when the syscall fails
  • Remove duplicate sycall constants
• Update clone fuzz test for MTCannon
• Add ExpectedMTState utility for validating full state of MTCannon
• Reorganize some test utils:
  • Move randomization logic into single- and multithreaded testutil packages
  • Break up some testutils across multiple files
• Organize syscall constants more consistently across on- and off-chain implementations

Metadata

• Fixes Add tests for new syscalls #11655
• Fixes Test edgecase where we move into wakeup traversal when the left thread stack is empty #11656
• Fixes Test edgecase where we pop the last thread due to exit syscall #11659
• Fixes Add tests for traversal behavior (normal and wakeup) #11657

[codecov]

Codecov Report

Attention: Patch coverage is 92.30769% with 30 lines in your changes missing coverage. Please review.

Project coverage is 84.83%. Comparing base (e9bc4ef) to head (c154483).
Report is 22 commits behind head on develop.

Files with missing lines	Patch %	Lines
cannon/mipsevm/multithreaded/testutil/mutators.go	67.44%	14 Missing ⚠️
cannon/mipsevm/testutil/rand.go	64.51%	9 Missing and 2 partials ⚠️
cannon/mipsevm/multithreaded/testutil/state.go	75.00%	2 Missing and 1 partial ⚠️
cannon/mipsevm/multithreaded/mips.go	75.00%	1 Missing ⚠️
cannon/mipsevm/multithreaded/testutil/thread.go	99.15%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #11605      +/-   ##
===========================================
+ Coverage    80.81%   84.83%   +4.02%     
===========================================
  Files           32       36       +4     
  Lines         2466     2777     +311     
===========================================
+ Hits          1993     2356     +363     
+ Misses         396      352      -44     
+ Partials        77       69       -8     

Flag	Coverage Δ
cannon-go-tests	84.83% <92.30%> (+4.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cannon/mipsevm/exec/mips_syscalls.go	93.66% <ø> (ø)
cannon/mipsevm/multithreaded/state.go	93.12% <100.00%> (ø)
...non/mipsevm/multithreaded/testutil/expectations.go	100.00% <100.00%> (ø)
cannon/mipsevm/singlethreaded/testutil/state.go	65.00% <100.00%> (-19.62%)	⬇️
cannon/mipsevm/testutil/mips.go	85.82% <100.00%> (+3.64%)	⬆️
cannon/mipsevm/testutil/state.go	73.25% <100.00%> (+1.12%)	⬆️
cannon/mipsevm/multithreaded/mips.go	96.21% <75.00%> (+24.74%)	⬆️
cannon/mipsevm/multithreaded/testutil/thread.go	99.15% <99.15%> (ø)
cannon/mipsevm/multithreaded/testutil/state.go	75.00% <75.00%> (-10.72%)	⬇️
cannon/mipsevm/testutil/rand.go	64.51% <64.51%> (ø)
... and 1 more

... and 3 files with indirect coverage changes

[Inphi]

Nice and thorough!