Adding feature file generation via Bazel

Change-Id: Ifa9cdf01c3129e5cd6cb7b8f4aee956eef9055f8
diff --git a/tools/build_rules/prelude_bazel b/tools/build_rules/prelude_bazel
index 2662c07..abdd0db 100644
--- a/tools/build_rules/prelude_bazel
+++ b/tools/build_rules/prelude_bazel
@@ -3,5 +3,6 @@
         "TEST_ADAPTERS", "TEST", "TEST_REST", "METRICS", "KRYO", "NETTY", "GRPC_1_3")
 
 load("//tools/build/bazel:osgi-java-library.bzl", "osgi_jar_with_tests", "osgi_jar", "wrapped_osgi_library")
+load("//tools/build/bazel:osgi_features.bzl", "osgi_feature")
 
 generated_java_libraries()