Implement Mutex Using Compare-And-Swap (CAS)

Implement a mutex using atomic compare-and-swap operations.

Requirements:

• Define mutex structure with atomic state
• Implement mutex_lock() using atomic_compare_exchange_strong
• Implement mutex_unlock() using atomic_store
• Implement mutex_trylock() (non-blocking attempt)
• Test with multiple threads incrementing a shared counter
• Demonstrate race condition WITHOUT mutex
• Demonstrate correct behavior WITH mutex
• Use pthreads for threading
• Use C11 atomic operations (stdatomic.h)
• Print lock acquire/release events
• Show final counter value (should match expected)