[packaging] libapr README url fix patch

[Boris Kolpackov]

Boris Kolpackov <boris at codesynthesis.com> writes:

> So, based on this, I would suggest that we wait to hear from Phil
> and then decide on the course of action.

Ok, I've heard back from Phil and he is keen to get build2 support
upstreamed.

So, as mentioned in my previous email, I would suggest that you use
the Boost.Predef PR as an example. I would also be happy to review
your work before you submit a PR upstream.

I've also browsed around the Catch2 repository and have a couple of
notes:

1. They seem to be moving to the <catch2/catch.hpp> inclusion scheme
   which is a good thing[1] and we should follow along. This seems to
   be only currently implemented for single_include/.

2. There are a couple of problematic entries in their .gitignore file,
   specifically, 'Build' and '*.build'.

   In fact, ignoring 'build/' appears to be a common practice in CMake-
   based projects and the fact that it makes conversion to build2 more
   difficult was mentioned to me before. There is an idea of supporting
   an alternative naming scheme for build2-related files and directories
   that I am planning to look into in the next few days. I will keep you
   posted about the results.

[1] https://build2.org/build2-toolchain/doc/build2-toolchain-intro.xhtml#proj-struct