Fix unresolved symbols when linking tools/clang/unittests/Tooling/ToolingTests

Summary: Add correct cmake dependencies so that `ToolingTests` link
successfully.

Patch by Guanzhong Chen

Reviewers: tlively, aheejin

Reviewed By: tlively

Subscribers: mgorny, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62333

llvm-svn: 361536