Merge releaseBufferEndpoint in LayerState

If T1 has a buffer update and gets merged into T2, where T2 modified the
same SC, we need to ensure releaseBufferEndpoint is also merged.

Test: split, pip
Fixes: 196198502
Change-Id: I836d32f4c439235a91a4c933a1b477813f6726a2
diff --git a/libs/gui/LayerState.cpp b/libs/gui/LayerState.cpp
index 5bed69c..8a7a871 100644
--- a/libs/gui/LayerState.cpp
+++ b/libs/gui/LayerState.cpp
@@ -463,6 +463,7 @@
     if (other.what & eBufferChanged) {
         what |= eBufferChanged;
         buffer = other.buffer;
+        releaseBufferEndpoint = other.releaseBufferEndpoint;
     }
     if (other.what & eAcquireFenceChanged) {
         what |= eAcquireFenceChanged;