This reverts commit 02ca096a85.
The clang-format binary is now included in the release tarball [0] and
we don't need to add it anymore. This fixes the following build error:
ln: failed to create symbolic link 'buildtools/linux64/clang-format': File exists
However, the build still fails a bit later in the configure phase.
[0]: https://bugs.chromium.org/p/chromium/issues/detail?id=1052503
fca8961bdb