Roll back recent change

Disable dropping of frames based on timestamp.  Resume auto-
generating timestamps in Surface.

Bug 10151804

Change-Id: I15de26158e1d7ef22a5b150e685a126dc48ae2b4
diff --git a/libs/gui/BufferQueue.cpp b/libs/gui/BufferQueue.cpp
index e22679e..88159aa 100644
--- a/libs/gui/BufferQueue.cpp
+++ b/libs/gui/BufferQueue.cpp
@@ -855,7 +855,7 @@
         //
         // NOTE: code assumes monotonic time values from the system clock are
         // positive.
-        while (mQueue.size() > 1) {
+        while (false && mQueue.size() > 1) {
             // If entry[1] is timely, drop entry[0] (and repeat).  We apply
             // an additional criteria here: we only drop the earlier buffer if
             // our desiredPresent falls within +/- 1 second of the expected