zsh: use autoreconf PKG_FIXUP to configure

zsh: use autoreconf PKG_FIXUP to configure

In preparation to PCRE2 fixup, use autoreconf PKG_FIXUP as a better
configure system instead of configure script. This is needed to reduce
upcoming patch to migrate to PCRE2 library.

To correctly use autoreconf it's needed to declare empty
PKG_REMOVE_FILES.

zsh include custom macro in the default aclocal.m4
When autoreconf PKG_FIXUP is used, if PKG_REMOVE_FILES is not defined,
it's set to remove the file aclocal.m4 by default resulting in problem
with the custom macro AC_PROG_LN.

Signed-off-by: Oskari Rauta <oskari.rauta@gmail.com>
[ split to 2 commit, add PKG_REMOVE_FILES, reword commit description ]
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>