Question: How to install units as a vendored library

[thorstenhater]

Hi,

I am using units as a git submodule (packaged versions seem not to be widely available, even for Spack).
As units are part of the public API, units needs to be installed along the main project in this setting.
However, I cannot set UNITS_INSTALL=ON in CMake, as cmake_dependent_option will override it
unless PROJECT_NAME is UNITS. Currently, I am overriding PROJECT_NAME, which is less than
desirable.

Could you relax this restriction by checking whether an installation is requested explicitly or, if I am misusing
CMake here, provide a description on what to do instead?