partitioning_systems: create libpartitioning_systemscommon for common files

Change-Id: I1b3c2f9bad60024a7a07ae4bbfe3970ac5ae42b4
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5632
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>