While LIRC's upstream doesn't provide .pc file with it, Debian does so and some software (ncmpc for example) require it to be built. Thus, I think we should include similar .pc file. Attached solution is based on putting the .pc file inside ${FILESDIR} and settings the correct version through sed.
Created attachment 197688 [details] .pc template
Created attachment 197692 [details, diff] Diff to ebuild
And closing as UPSTREAM. It's not distributions job to include pkg-config files, the file should come from upstream.