Added clangLex to the dependencies for clang-import-test.

This is part of the effort to get the i686-mingw32-RA-on-linux bot to like clang-import-test.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@290010 91177308-0d34-0410-b5e6-96231b3b80d8