[PATCH] fix build failure when configured using --without-zlib

All,

AFAIK, Subversion cannot be build without zlib. At present if configured
using '--without-zlib' or '--with-zlib=no' options, build will fail with
following error message ...
[[[
Subversion/trunk/libtool: line 4992: cd: no/lib: No such file or
directory
libtool: link: cannot determine absolute directory name of `no/lib'
]]]

[[[
Fixes build failure when configured with '--without-zlib'.

* build/ac-macros/zlib.m4
  (SVN_LIB_Z): Configure error-outs if executed with '--without-zlib'
   or '--with-zlib=no' options.

Patch by: Alexander Thomas <alexander_at_collab.net>
]]]

-Alexander Thomas(AT)