Then what you have is a fork of the library. There is no reason you can't distribute forks of the library (to either your own paths or with your own modified names) using the system package manager.
If you are expecting the person taking your patches to install them to the system, however, that's a whole 'nother ball game, and gets back to the original point: as a system administrator, I have no reason to believe your "better" versions of those libraries are going to interoperate with everything else on the system, and I am then going to have to do a bunch of work doing that isolation myself.
If you are expecting the person taking your patches to install them to the system, however, that's a whole 'nother ball game, and gets back to the original point: as a system administrator, I have no reason to believe your "better" versions of those libraries are going to interoperate with everything else on the system, and I am then going to have to do a bunch of work doing that isolation myself.