create PLIST awk substitution patterns for directories created by the
current package. This is particularly useful for base packages that
create a directory structure that is then used by subsequent (dependent)
packages.
a buildlink.mk from a package's Makefile and PLIST.
XXX: this is an attempt to make the creation of buildlink.mk files more
XXX: systematic and less error-prone than copying existing buildlink.mk
XXX: files and modifying them for a new package. Any help in making this
XXX: script less simplistic and more versatile is gladly welcome!