Depending on the processing order of rules when installing in parallel,
these install rules might be processed before some other rule happens
to create the respective dirs. Make sure each one creates the needed
dirs before installing into them.
For about half the ports, we don't need a subdir configure script.
They're using the config/default.m[ht] rules, and they aren't doing
any unique configure tests, so they exist just to pass top-level
settings down to create the arch Makefile. We can just as easily
do that from the top-level Mkaefile directly and skip configure.
Most of the remaining configure scripts could be migrated up to
the top-level too, but that would require care in each subdir.
So let's be lazy and put that off to another day.