Show build config in dumpsys SurfaceFlinger

This adds a line to the "dumpsys SurfaceFlinger" output that shows
build-time configuration values.

Example:
 Build configuration: [sf HAS_CONTEXT_PRIORITY] [libui] \
  [libgui USE_FENCE_SYNC]

Bug 7206633

Change-Id: Ibe1856b459d34a4be6ee83a4ebfd2807e6cc68a0
diff --git a/libs/gui/Android.mk b/libs/gui/Android.mk
index 282c25a..923845c 100644
--- a/libs/gui/Android.mk
+++ b/libs/gui/Android.mk
@@ -24,7 +24,8 @@
 	SurfaceComposerClient.cpp \
 	DummyConsumer.cpp \
 	CpuConsumer.cpp \
-	BufferItemConsumer.cpp
+	BufferItemConsumer.cpp \
+	GuiConfig.cpp
 
 LOCAL_SHARED_LIBRARIES := \
 	libbinder \