libui: flush hwbinder commands in Allocator::allocate

Bug: 36279079
Test: monkey test on fugu
Change-Id: I81f72d63d3ede64f279b26208bb5df7646050e73
diff --git a/libs/ui/Android.bp b/libs/ui/Android.bp
index 5ccf178..406968d 100644
--- a/libs/ui/Android.bp
+++ b/libs/ui/Android.bp
@@ -72,6 +72,7 @@
         "libhardware",
         "libhidlbase",
         "libhidltransport",
+        "libhwbinder",
         "libsync",
         "libutils",
         "liblog",