libreadline and Debian 5 - not missing just badly named

I've just had the common problem with not finding the readline library
while compiling/linking 8.4.4 on a new linux (Debian 5 - lenny). Nothing
seemed to work: --with-libraries=/lib and pointing CFLAGs there all
failed to find readline. The installed packages though said that it was
present.

The problem was that this linux had libreadline.so.5.2 with the symlink
libreadline.so.5 not libreadline.so. In other words the link had too
specific a name for the configure checks.

Simple solution: create the correct symlink - libreadline.so

Also needed a similar fix for libz.

It may be a problem with some *nixes, or versions, or with the
particular packages installed/not installed.

Janet