graphics: add a default implementation for IComposer

The default implementatoin is built on top of conventional hwcomposer2.

Test: make
Change-Id: Ia4f13b1d682462769056679fc0aae82a75cb53d2
diff --git a/graphics/composer/2.1/default/Android.bp b/graphics/composer/2.1/default/Android.bp
new file mode 100644
index 0000000..f91c9a2
--- /dev/null
+++ b/graphics/composer/2.1/default/Android.bp
@@ -0,0 +1,16 @@
+cc_library_shared {
+    name: "android.hardware.graphics.composer@2.1-impl",
+    relative_install_path: "hw",
+    srcs: ["Hwc.cpp"],
+    shared_libs: [
+        "android.hardware.graphics.allocator@2.0",
+        "android.hardware.graphics.composer@2.1",
+        "libbase",
+        "libcutils",
+        "libhardware",
+        "libhidl",
+        "libhwbinder",
+        "liblog",
+        "libutils",
+    ],
+}