Revert "Fix the build broken as a result of deleting jit from LLVM."

jit was re-added back to LLVM, so now we require to link against it
again.  Should it get removed again, then revert this revert.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@215170 91177308-0d34-0410-b5e6-96231b3b80d8