clean-up unneeded code

now that we removed the notion of a "inUse" buffer in surfaceflinger
a lot of code can be simplified / removed.

noteworthy, the whole concept of "unlockClient" wrt. "compositionComplete"
is also gone.

Change-Id: I210413d4c8c0998dae05c8620ebfc895d3e6233d
diff --git a/include/private/surfaceflinger/SharedBufferStack.h b/include/private/surfaceflinger/SharedBufferStack.h
index 9d589cf..eb599b5 100644
--- a/include/private/surfaceflinger/SharedBufferStack.h
+++ b/include/private/surfaceflinger/SharedBufferStack.h
@@ -105,7 +105,7 @@
     volatile int32_t head;      // server's current front buffer
     volatile int32_t available; // number of dequeue-able buffers
     volatile int32_t queued;    // number of buffers waiting for post
-    volatile int32_t inUse;     // buffer currently in use by SF
+    volatile int32_t reserved1;
     volatile status_t status;   // surface's status code
 
     // not part of the conditions
@@ -275,7 +275,6 @@
             int32_t identity);
 
     ssize_t retireAndLock();
-    status_t unlock(int buffer);
     void setStatus(status_t status);
     status_t reallocateAll();
     status_t reallocateAllExcept(int buffer);
@@ -356,12 +355,6 @@
         inline const char* name() const { return "BuffersAvailableCondition"; }
     };
 
-    struct UnlockUpdate : public UpdateBase {
-        const int lockedBuffer;
-        inline UnlockUpdate(SharedBufferBase* sbb, int lockedBuffer);
-        inline ssize_t operator()();
-    };
-
     struct RetireUpdate : public UpdateBase {
         const int numBuffers;
         inline RetireUpdate(SharedBufferBase* sbb, int numBuffers);