Update BackgroundExecutor to use LocklessQueue

This change allows BackgroundExecutor to receive callbacks from multiple
producers.

Bug: 283133164
Test: BackgroundExecutorTest
Change-Id: I63f3266184a2ae90b15d7d1b7d9502847e268763
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index 70f8a83..881b362 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -71,6 +71,7 @@
         ":libsurfaceflinger_sources",
         "libsurfaceflinger_unittest_main.cpp",
         "ActiveDisplayRotationFlagsTest.cpp",
+        "BackgroundExecutorTest.cpp",
         "CompositionTest.cpp",
         "DisplayIdGeneratorTest.cpp",
         "DisplayTransactionTest.cpp",