Migrate libvulkan to ndk_library.

Test: make native
Bug: http://b/30465923
Change-Id: I97199a600b71447fd14181e06be3f9221c2529f3
diff --git a/Android.bp b/Android.bp
index d402651..086a2c6 100644
--- a/Android.bp
+++ b/Android.bp
@@ -10,4 +10,5 @@
     "libs/*",
     "opengl",
     "services/*",
+    "vulkan",
 ]