Add vendor variant of libtextclassifier_hash_static for libneuralnetworks_common

I'm trying to switch all NNAPI libraries to use the libtextclassifier_hash_static.
Otherwise, Soong sees both libtextclassifier_hash & libtextclassifier_hash_static as
com.android.neualnetworks dependencies, while we need only need one,
the static variant.

Test: build crosshatch & flashed device.
Bug: 148593574
Change-Id: If0850fc4309c734d4bf522b661efac9638fd8886
diff --git a/Android.bp b/Android.bp
index 0962f2a..c78aaf5 100644
--- a/Android.bp
+++ b/Android.bp
@@ -42,6 +42,7 @@
 cc_library_static {
     name: "libtextclassifier_hash_static",
     defaults: ["libtextclassifier_hash_defaults"],
+    vendor_available: true,
     sdk_version: "current",
     stl: "libc++_static",
 }