libgui: Add bq_gl_fence_cleanup flag

Bug: 339705065
Flag: EXEMPT new flag
Test: n/a

Change-Id: I06cf8bce5af75cc9eb9c462e953cf13a6bfde7c1

Author: Jim Shargo

libs/gui/libgui_flags.aconfig

@@ -131,3 +131,11 @@ flag {
   bug: "359252619"
   is_fixed_read_only: true
 } # bq_producer_throttles_only_async_mode
+
+flag {
+  name: "bq_gl_fence_cleanup"
+  namespace: "core_graphics"
+  description: "Remove BufferQueueProducer::dequeue's wait on this fence (or the fence entirely) to prevent deadlocks"
+  bug: "339705065"
+  is_fixed_read_only: true
+} # bq_gl_fence_cleanup