mod_fastcgi DSO with RedHat Enterprise Linux 3.0

So while playing with Ruby on Rails, I've been trying to get mod_fastcgi to work with my RHEL AS release 3 (Taroon Update 4) install. Lots of undefined reference to various apr_* calls, the whole apache runtime libs. I was using apxs just like I should have. The best hints I could find was "don't use apxs" and use the latest mod_fastcgi-SNAP (2.4.3) which has a sample Makefile.AP2 to get it to compile. Here is the key for the RedHat stock apache setup:

top_dir      = /usr/lib/httpd

This will point to the right apache .mk files so that you will get the proper libraries linked in. After that, it's all the same standard stuff. This tip for debian led me to my fix.