Use std::unique_ptr in ClangTidyCheckFactories

I had to explicitly define some destructors that could only be defined
in the corresponding .cpp files.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@372978 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed