ART: Simplify atomic.h

Prefer std::atomic operations over wrappers in atomic.h. Exceptions
are cases that relate to the Java data memory operations and CAS
operations.

Bug: 71621075
Test: art/test.py --host -j32
Test: art/test.py --target --64 -j4
Change-Id: I9a157e9dede852c1b2aa67d22e3e604a68a9ef1c
diff --git a/runtime/thread_pool_test.cc b/runtime/thread_pool_test.cc
index 895a108..d784200 100644
--- a/runtime/thread_pool_test.cc
+++ b/runtime/thread_pool_test.cc
@@ -71,7 +71,7 @@
   // Wait for tasks to complete.
   thread_pool.Wait(self, true, false);
   // Make sure that we finished all the work.
-  EXPECT_EQ(num_tasks, count.LoadSequentiallyConsistent());
+  EXPECT_EQ(num_tasks, count.load(std::memory_order_seq_cst));
 }
 
 TEST_F(ThreadPoolTest, StopStart) {
@@ -84,7 +84,7 @@
   }
   usleep(200);
   // Check that no threads started prematurely.
-  EXPECT_EQ(0, count.LoadSequentiallyConsistent());
+  EXPECT_EQ(0, count.load(std::memory_order_seq_cst));
   // Signal the threads to start processing tasks.
   thread_pool.StartWorkers(self);
   usleep(200);
@@ -93,7 +93,7 @@
   thread_pool.AddTask(self, new CountTask(&bad_count));
   usleep(200);
   // Ensure that the task added after the workers were stopped doesn't get run.
-  EXPECT_EQ(0, bad_count.LoadSequentiallyConsistent());
+  EXPECT_EQ(0, bad_count.load(std::memory_order_seq_cst));
   // Allow tasks to finish up and delete themselves.
   thread_pool.StartWorkers(self);
   thread_pool.Wait(self, false, false);
@@ -157,7 +157,7 @@
   thread_pool.AddTask(self, new TreeTask(&thread_pool, &count, depth));
   thread_pool.StartWorkers(self);
   thread_pool.Wait(self, true, false);
-  EXPECT_EQ((1 << depth) - 1, count.LoadSequentiallyConsistent());
+  EXPECT_EQ((1 << depth) - 1, count.load(std::memory_order_seq_cst));
 }
 
 class PeerTask : public Task {