Add option FUNCHOOK_INSTALL

[rumblehhh]

FUNCHOOK_INSTALL allows skipping Funchook's install step

[kubo]

@rumblehhh Could you post a use case of the option? What problem is avoided by it?

[rumblehhh]

Sure, we're using funchook-static as a private dependency of a project and we have no need for funchook to be installed alongside our project. Users of our project don't need headers or libraries from funchook and they aren't needed after the build process (static linking).
If we were using funchook-shared or if funchook was being used a public dependency then we would have a need for the installed files.

I believe its reasonably common for libraries such as these to provide an install/skip install option.

[kubo]

Thanks. I got it.