Mark the module as VNDK or VNDK-SP in Android.bp

As a VNDK/VNDK-SP module, Android.bp must have 'vndk' tag as well
as 'vendor_available: true'.

For a VNDK module, the 'vndk' tag has 'enabled: true'.
It will be installed system/lib(64)/vndk as a vendor variant.

For a VNDK-SP module, the 'vndk' tag has
'support_system_process: true' as well as 'enabled: true'.
It will be installed system/lib(64)/vndk-sp as a vendor variant.

Bug: 63866913
Test: build and boot with BOARD_VNDK_VERSION=current
Change-Id: I8224b954f786fa51c1ead89e95d284d355e9cb72
diff --git a/Android.bp b/Android.bp
index 8d5c848..766c5ef 100644
--- a/Android.bp
+++ b/Android.bp
@@ -17,6 +17,9 @@
     clang: true,
     host_supported: true,
     vendor_available: true,
+    vndk: {
+        enabled: true,
+    },
 
     cflags: [
         "-Wno-unused-parameter",