Make libdng_sdk vendor available.

This means that both system and vendor libraries
can link against it when the vndk is enabled (when
BOARD_VNDK_VERSION=current is set.

Test: build libdng_sdk with BOARD_VNDK_VERSION=current
Bug: 37342627
Change-Id: Ib585e45c3a16afce9df1c2e0af30211aae703ed5
diff --git a/Android.bp b/Android.bp
index 65c7c51..8d37d9a 100644
--- a/Android.bp
+++ b/Android.bp
@@ -100,6 +100,7 @@
 
 cc_library{
     name: "libdng_sdk",
+    vendor_available: true,
     defaults: ["libdng_sdk-defaults"],
 
     cflags: ["-DqDNGValidate=0"],