[llvm-dev] [Zorg] Simplify ClangBuilder

[Renato Golin via llvm-dev]

Hi Richard, Marco,

I noticed that you two are the remaining bot owners using the
`getClangBuildFactory` from `ClangBuilder`. All the other bots using
that builder have moved to the new `getClangCMakeBuildFactory`,
including Windows ones.

Given that they do similar functionalities, I'd like to encourage you
to move to the new factory, so that we can simplify the builder's
code.

Thanks!
--renato

PS: The builders are:

Richard:
http://lab.llvm.org:8011/builders/clang-x86_64-linux-selfhost-modules-2
http://lab.llvm.org:8011/builders/clang-x86_64-linux-selfhost-modules

Marco:
http://lab.llvm.org:8011/builders/clang-bpf-build