don't return the current buffer from dequeueBuffer

we were not reseting mCurrentTexture in some situations
which in turn caused dequeueBuffers() return a
"FREE" buffer that was also current.
Very often it was harmless, but it created a race with
updateTexImage() which could cause the following
queueBuffers() to fail.

Bug: 5156325
Change-Id: If15a31dc869117543d220d6e5562c57116cbabdb
diff --git a/include/gui/SurfaceTexture.h b/include/gui/SurfaceTexture.h
index a6fb12e..493993d 100644
--- a/include/gui/SurfaceTexture.h
+++ b/include/gui/SurfaceTexture.h
@@ -275,7 +275,7 @@
         enum BufferState {
             // FREE indicates that the buffer is not currently being used and
             // will not be used in the future until it gets dequeued and
-            // subseqently queued by the client.
+            // subsequently queued by the client.
             FREE = 0,
 
             // DEQUEUED indicates that the buffer has been dequeued by the