graphics: convert composer default impl to a library

Convert composer default impl to a header-only library,
android.hardware.graphics.composer@2.1-passthrough.

Test: builds and VTS
Change-Id: I9251aadc28816fc4c1d9326e09e297f30e9c25fe
diff --git a/graphics/composer/2.1/utils/passthrough/Android.bp b/graphics/composer/2.1/utils/passthrough/Android.bp
new file mode 100644
index 0000000..4d3c976
--- /dev/null
+++ b/graphics/composer/2.1/utils/passthrough/Android.bp
@@ -0,0 +1,22 @@
+cc_library_headers {
+    name: "android.hardware.graphics.composer@2.1-passthrough",
+    defaults: ["hidl_defaults"],
+    vendor: true,
+    shared_libs: [
+        "libhardware",
+        "libhwc2on1adapter",
+        "libhwc2onfbadapter",
+    ],
+    export_shared_lib_headers: [
+        "libhardware",
+        "libhwc2on1adapter",
+        "libhwc2onfbadapter",
+    ],
+    header_libs: [
+        "android.hardware.graphics.composer@2.1-hal",
+    ],
+    export_header_lib_headers: [
+        "android.hardware.graphics.composer@2.1-hal",
+    ],
+    export_include_dirs: ["include"],
+}