Log Message:
* Introduce BLACKDOWN_ARCH, which is usually just ${MACHINE_ARCH}
  (but is "ppc" on powerpc), and use it instead of MACHINE_ARCH where
  applicable.

* Introduce BLACKDOWN_REL, which is usually just "FCS-02b" (but is
  "rc1" on arm).

* Simplify how MASTER_SITES and DISTFILES get defined.

* Improve some formatting.

* Replace literal "i386" in PLIST with ${BLACKDOWN_ARCH}.

* Adjust bin/.java_wrapper for powerpc platforms, and update the
  similar patch for bin/realpath.

On NetBSD/powerpc, this greatly reduces noise during package
installation, and gets us further at runtime. Believe it or not,
seeing "/lib/libc.so.6: version `GLIBC_2.2' not found" is an
improvement.