Support of lldb on Kfreebsd

Summary: Patch by Pino Toscano. Reported in http://bugs.debian.org/835665

Reviewers: tfiala, emaste

Subscribers: beanz, mgorny, emaste, krytarowski, brucem, tberghammer, danalbert, srhines, #lldb

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D23977