libc shouldn't need perl to build

The license extraction code for libc relies on perl. While the perl code is lots faster than the KSH93 code I wrote, the fact that it runs in about 2 seconds shouldn't be terribly disconcerting. (The perl code runs in about .15 seconds.).

Reducing the dependency is preferable here. It may be worth considering rewriting this in C or something like that at some point in the future. (Go would be natural, but I'm not ready to introduce Go at this stage.)