Add Mojo{Set,Get}DataPipeProducerOptions() to the NaCl system thunks.

This is just like 58ec2b7917fbe3241e9352fc338990aae878c72c, but for
producer options rather than consumer (and I didn't mess up adding the
native system thunks).

R=vardhan@google.com
BUG=#442

Review URL: https://codereview.chromium.org/1876353006 .
diff --git a/mojo/edk/embedder/system_impl_private_entrypoints.cc b/mojo/edk/embedder/system_impl_private_entrypoints.cc
index 0e62599..1ec1da9 100644
--- a/mojo/edk/embedder/system_impl_private_entrypoints.cc
+++ b/mojo/edk/embedder/system_impl_private_entrypoints.cc
@@ -162,6 +162,27 @@
                               MakeUserPointer(data_pipe_consumer_handle));
 }
 
+MojoResult MojoSystemImplSetDataPipeProducerOptions(
+    MojoSystemImpl system,
+    MojoHandle data_pipe_producer_handle,
+    const struct MojoDataPipeProducerOptions* options) {
+  mojo::system::Core* core = static_cast<mojo::system::Core*>(system);
+  DCHECK(core);
+  return core->SetDataPipeProducerOptions(data_pipe_producer_handle,
+                                          MakeUserPointer(options));
+}
+
+MojoResult MojoSystemImplGetDataPipeProducerOptions(
+    MojoSystemImpl system,
+    MojoHandle data_pipe_producer_handle,
+    struct MojoDataPipeProducerOptions* options,
+    uint32_t options_num_bytes) {
+  mojo::system::Core* core = static_cast<mojo::system::Core*>(system);
+  DCHECK(core);
+  return core->GetDataPipeProducerOptions(
+      data_pipe_producer_handle, MakeUserPointer(options), options_num_bytes);
+}
+
 MojoResult MojoSystemImplWriteData(MojoSystemImpl system,
                                    MojoHandle data_pipe_producer_handle,
                                    const void* elements,