Now this is what I was thinking: build a proper XS module instead of using the Inline::C shortcut. No reason to force compilation on the web server process, especially if it doesn't work properly anyway.

As a general question, I was wondering how Inline::C is used in production applications. My instinct is that Inline::C is more of a helper/get-me-started module, not something to be used in the final shipped application. Seeing how the OP solved the original problem confirms it for me: library and header include paths shouldn't be hard-coded in the Perl code; stuff like that belongs in a build process.

On the other hand, my impression is that Inline::C is a very popular module. Is it accepted practice to include C code using it? Would I find modules on CPAN that depend on Inline::C?

We do have some Perl at $work, but mostly just for utility scripts, and we've never had to write any C code. I'm curious what the general accepted practice is in the Perl community.