Add missing libraries to unittest link

Summary:
Currently, linking of the unittests fails on linux because it is missing a bunch of symbols from
libedit, curses, etc. This fixes the build by adding the correct dependencies.

Test Plan: Linking works, unit tests run.

Reviewers: zturner

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D9244

llvm-svn: 235853