Allowlist external/libtextclassifier for sdk_variant_only.

Bug: 166040889
Change-Id: If8a9d916dada116f52fd84194fa42e9179526b2c
diff --git a/android/neverallow.go b/android/neverallow.go
index 41b399a..af072cd 100644
--- a/android/neverallow.go
+++ b/android/neverallow.go
@@ -174,6 +174,7 @@
 		"tools/test/graphicsbenchmark/apps/sample_app",
 		"tools/test/graphicsbenchmark/functional_tests/java",
 		"vendor/xts/gts-tests/hostsidetests/gamedevicecert/apps/javatests",
+		"external/libtextclassifier/native",
 	}
 
 	platformVariantPropertiesAllowedList := []string{