CMake vs. configure and packaging on different platforms

OK, I'm looking into how to add a libtooling package and I have a
couple questions.

On Windows, our only choice is CMake for building project/solution
files for building.

What does CMake do for packaging on Windows?

On unix, we can use CMake or we can use llvm/configure. Why do we
have two ways of configuring and building on linux? What do we get
from configure that we don't get from CMake?

Does this imply that I need to add packaging instructions in two place
for unix?

OK, I'm looking into how to add a libtooling package and I have a
couple questions.

On Windows, our only choice is CMake for building project/solution
files for building.

What does CMake do for packaging on Windows?

The CMake build provides the "package" target. That target will take
everything that's part of the "install" target, and use NSIS (which
has to be installed separately) to bake that into an installer. See
CMakeLists.txt:42 ("Configure CPack").

On unix, we can use CMake or we can use llvm/configure. Why do we
have two ways of configuring and building on linux? What do we get
from configure that we don't get from CMake?

Does this imply that I need to add packaging instructions in two place
for unix?

Since we can build libtooling with both build systems, it would be
nice if it could be packaged by both build systems. However, I don't
think anyone would object if you just started with one of them.

- Hans