Add an option retention option to proto_library.

PiperOrigin-RevId: 521533139
Change-Id: Icda0b4a952703196084ca13ca2f0c33cbceb0c40
diff --git a/src/main/starlark/builtins_bzl/common/proto/proto_library.bzl b/src/main/starlark/builtins_bzl/common/proto/proto_library.bzl
index f497a77..bbd4991 100644
--- a/src/main/starlark/builtins_bzl/common/proto/proto_library.bzl
+++ b/src/main/starlark/builtins_bzl/common/proto/proto_library.bzl
@@ -220,6 +220,8 @@
     args = ctx.actions.args()
     if ctx.fragments.proto.experimental_proto_descriptorsets_include_source_info():
         args.add("--include_source_info")
+    if hasattr(ctx.attr, "_retain_options") and ctx.attr._retain_options:
+        args.add("--retain_options")
 
     strict_deps_mode = ctx.fragments.proto.strict_proto_deps()
     strict_deps = strict_deps_mode != "OFF" and strict_deps_mode != "DEFAULT"