pax -rw, the destination directory must exist. pax in NetBSD creates it if
not, pax in MirBSD complains. I read through all pkgsrc Makefiles that use
pax and added an entry to INSTALLATION_DIRS, or an INSTALL_DATA_DIR
invocation.
I did not test all the changes but they should be fairly safe. If you notice
any breakage because of this change, please contact me.