lldb: Fix compilation on OpenBSD

Summary: Update the OpenBSD Host.cpp for the new SetFile() function signature. Fixes compiling lldb on OpenBSD.

Reviewers: krytarowski

Reviewed By: krytarowski

Subscribers: lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D57907

llvm-svn: 353642