libgui: add BufferQueue test infrastructure

This change adds some infrastructure for testing the BufferQueue class.  It
also includes a test that tests the new check in BufferQueue::acquireBuffer
that prevents the consumer from acquiring more than one buffer beyond the max
acquired buffer count that was set.

Change-Id: I38554ad3f9a53d2ddeba7ef0deee35ec2e2f9775
diff --git a/libs/gui/tests/Android.mk b/libs/gui/tests/Android.mk
index e8863d3..4a6f74f 100644
--- a/libs/gui/tests/Android.mk
+++ b/libs/gui/tests/Android.mk
@@ -7,6 +7,7 @@
 LOCAL_MODULE_TAGS := tests
 
 LOCAL_SRC_FILES := \
+    BufferQueue_test.cpp \
     CpuConsumer_test.cpp \
     SurfaceTextureClient_test.cpp \
     SurfaceTexture_test.cpp \