Fix build broken as a result of r213171.

r213171 renames the 'clangRewriteCore' library to 'clangRewrite'.
This change simply updates the makefiles to reference the correct
library name.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@213181 91177308-0d34-0410-b5e6-96231b3b80d8