SF: Cleanups to use std::atomic/std::mutex

A few places in the code used "volatile". This patch removes the
volatile.

In most of the cases, the volatile value was converted to a std::atomic
value. The exception was Barrier where it was not actually necessary,
but there I converted the code to use std::mutex.

Bug: None
Test: atest SurfaceFlinger_test CtsViewTestCases
Change-Id: I7b4f5a7398a241db8201dc7f60d7c9cd41e32e1b
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index bfadf6e..a300857 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -794,7 +794,7 @@
     // access must be protected by mStateLock
     mutable Mutex mStateLock;
     State mCurrentState{LayerVector::StateSet::Current};
-    volatile int32_t mTransactionFlags;
+    std::atomic<int32_t> mTransactionFlags{0};
     Condition mTransactionCV;
     bool mTransactionPending;
     bool mAnimTransactionPending;
@@ -813,8 +813,7 @@
     bool mLayersRemoved;
     bool mLayersAdded;
 
-    // access must be protected by mInvalidateLock
-    volatile int32_t mRepaintEverything;
+    std::atomic<bool> mRepaintEverything{false};
 
     // helper methods
     void configureHwcCommonData(const CompositionInfo& compositionInfo) const;