* Remove support for the "common" installation location from packagefs,
package kit, package daemon, package managers.
* Rename the B_COMMON_*_DIRECTORY constants referring to writable
directories to B_SYSTEM_*_DIRECTORY.
* Remove/adjust the use of various B_COMMON_*_DIRECTORY constants.
I'm sure some occurrence still remain. They can be adjusted when the
remaining B_COMMON_*_DIRECTORY constants are removed.