[gn build] Add build files for llvm-cat, llvm-lto, llvm-lto2, llvm-modextract,...

[gn build] Add build files for llvm-cat, llvm-lto, llvm-lto2, llvm-modextract, llvm-profdata, llvm-symbolizer

These are the llvm/tools needed by check-clang.

Differential Revision: https://reviews.llvm.org/D56018

llvm-svn: 349989