Building postgresql 8.1.0: trouble finding readline, libz, etc

[Matt England <mengland@mengland.net>]

While building postgresql 8.1.0 from source on Debian Sarge, I'm finding 
the postgresql ./configure script can not find libreadling, libz, and 
associated include/header files.

I can make at least some of these problems go away if I do things like tell 
./configure about CFLAGS=-L/lib and also sym-link /lib/libreadline.so to 
/lib/libreadline5.so ...etc.

But these things seem like hacks.

Anybody know of how to solve this problem in a more-elegant fashion?

-Matt