[HWASAN] Modified __hwasan::Thread::unique_id_ to be u32 instead of u64.

[kstoimenov]

Summary

This is needed for LSAN integration work. LSAN uses context to store thread_id << 32 + stack_id. In order to fit both we would need thread_id to be 32 bit.

compiler-rt/lib/hwasan/hwasan_thread.h

public:
   HeapAllocationsRingBuffer *heap_allocations() { return heap_allocations_; }
   StackAllocationsRingBuffer *stack_allocations() { return stack_allocations_; }
 
   tag_t GenerateRandomTag(uptr num_bits = kTagBits);
 
   void DisableTagging() { tagging_disabled_++; }
   void EnableTagging() { tagging_disabled_--; }
 
-  u64 unique_id() const { return unique_id_; }
+  u32 unique_id() const { return unique_id_; }
   void Announce() {
     if (announced_) return;
     announced_ = true;
     Print("Thread: ");
   }
 
   uptr &vfork_spill() { return vfork_spill_; }
 
private:
 
   u32 random_state_;
   u32 random_buffer_;
 
   AllocatorCache allocator_cache_;
   HeapAllocationsRingBuffer *heap_allocations_;
   StackAllocationsRingBuffer *stack_allocations_;
 
-  u64 unique_id_;  // counting from zero.
+  u32 unique_id_;  // counting from zero.
 
   u32 tagging_disabled_;  // if non-zero, malloc uses zero tag in this thread.
 
   bool announced_;
 
   bool random_state_inited_;  // Whether InitRandomState() has been called.
 
   friend struct ThreadListHead;