[clang] [cmake] Use add_clang_tool() to install all tools

Switch clang-check, clang-extdef-mapping and clang-offload-bundler
to use add_clang_tool() rather than add_clang_executable() with a custom
install rule.  This makes them LLVM_DISTRIBUTION_COMPONENTS-friendly.

Differential Revision: https://reviews.llvm.org/D68429

llvm-svn: 373785