[MCJIT] Update CMakeLists.txt for llvm-rtdyld to add Object as a requirement.

Hopefully this will fix
http://bb.pgr.jp/builders/clang-3stage-x86_64-linux/builds/8271/steps/stage1_build/logs/stdio



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222866 91177308-0d34-0410-b5e6-96231b3b80d8