[PATCH] Added doxygen support for the tools of clang-tools-extra repo

[Ariel Bernal]

  I noticed that the sphinx docs are generated in the source tree while the doxygen docs are copy over to the build tree (for llvm/clang), Does anyone know if there is any limitation on moving the sphinx docs to the build tree? I don't know how clang.llvm.org/extra/index.html gets updated.

http://llvm-reviews.chandlerc.com/D451