Completely overhaul the zsh package.

- Get rid of useless Makefile.common and pointless variables since there is
  no longer a zsh-current package.

- Remove non-standard per-OS non-checksummed patch file in FILESDIR.
  Integrate it correctly in the normal way.

- Ensure our patched configure.ac is actually regenerated.

- Use REPLACE_INTERPRETER instead of homegrown subst replacements.

- Remove esoteric and fragile configuration variables, a bunch of legacy OS
  based options, and simply depend correctly on terminfo and curses.

- Remove custom test targets and requirements for root access, the test suite
  works fine as a non-root user and can be done in the normal way.

- Use options.mk

- Set maintainer to pkgsrc-users, uebayasi resigned.

Fixes build on at least SunOS.  Tested on SunOS, Darwin, NetBSD (with and
without the "static" option), and Linux.

(jperkin)