Add ThreadSanitizer support and fixed identified data races

[fcostaoliveira]

This PR adds ThreadSanitizer (TSAN) support to memtier_benchmark for detecting and preventing data races in multi-threaded code.

Changes

Build System

• Added --enable-thread-sanitizer configure option
• Mutually exclusive with --enable-sanitizers (ASAN/LSAN)
• Automatically applies TSAN compiler flags: -fsanitize=thread -fno-omit-frame-pointer -O1

CI Integration

• New GitHub Actions workflow (.github/workflows/tsan.yml)
• Runs on all pushes and pull requests
• Uses setarch -R to disable ASLR (required for TSAN on kernel 6.6+)
• Tests OSS TCP, OSS TCP TLS, and OSS-CLUSTER configurations

Bug Fixes

• Fixed data race on m_finished flag using std::atomic<bool>
• Fixed data race on m_last_error in server_addr using std::atomic<int>
• Both fixes have zero performance overhead on x86/x64

Suppressions

• Added tsan_suppressions.txt for known benign data races
• Suppresses races on stats counters used only for progress display
• Final benchmark results remain race-free (collected after pthread_join)

Documentation

• Updated README with TSAN build and test instructions
• Documented suppression file usage
• Added code comments explaining benign races

Testing

Build with TSAN:

./configure --enable-thread-sanitizer
make

Run tests with TSAN:

TSAN_OPTIONS="suppressions=$(pwd)/tsan_suppressions.txt" setarch `uname -m` -R ./tests/run_tests.sh