[clang-reorder-fields] Switch to add_clang_tool
[clang-reorder-fields] Switch to add_clang_tool

`add_clang_tool` invokes `add_clang_executable` internally, but it also
takes care of setting up the install rule. It also adds an `install-*`
build target, which is required for `LLVM_DISTRIBUTION_COMPONENTS`.

Differential Revision: https://reviews.llvm.org/D39523

git-svn-id: a34e9779ed74578ad5922b3306b3d80a0c825546@317149 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra,llvm-mirror/clang-tools-extra