Removed the DIST_SUBDIR statement.
Log4j has been the first port from the Jakarta series and back then I thought
it would be useful to put all distfiles from the Jakarta project in the same
subdirectory. Now I don't think it is such a good idea. Furthermore, the ports
of other Jakarta projects do not use this scheme.
So here is a patch to fix it. I didn't bump the PORT_REVISION as there is no
point in updating the port if already installed.
I'll handle this.