Gregor Herrmann writes:
Alien::Build is already questionable¹, although I admit that patching the requirement out can be a bit cumbersome [...] ¹ it's great for e.g. Windows where building C libraries is a pain but on Debian it's problematic as downloading stuff from the internet is not something we can or want to do
Usually, Alien::Build does only download files if a library or its development files aren't available on the system. This is not only true for Windows but also for CPAN smokers. If libalien-build-perl is only used to build other Debian packages, neither a dependency on Mozilla::CA nor ca-certificates is required.
If you would like to write portable Perl modules that link to a C library, you can either add the library's source code to your module, which DBD::SQLite does for example, or use Alien::Build. Even with Alien::Build, I had to adapt one of my XS modules to weird CPAN smokers with C compilers with optimizer bugs, strange include and library paths, broken math on some architectures etc.