[lld] Treat .openbsd.randomdata as read-only

From: Rui Ueyama <ruiu@google.com>
Date: Mon, 19 Dec 2016 20:08:59 -0600

LGTM

Great. I don't have commit access, so it would be great if you could
commit this change for me.

Just realized that that I should have sent this to llvm-commits
instead. Apologies for that.

I have some further fixes. Is Phabricator preferred these days for
submitting patches?

Thanks,

Mark

Hi Mark,

committed with testcase r290174.
Yes, we usually use phab as it is convinent for doing reviews.

George.