Update editorconfig core to v0.12.0

So… this stores `libpcre` directly in the repo, which seems somewhat non-ideal. However, the only other option I can think of seems kind of lame, too:

Detect, via script, what `libpcre` cmake finds for EditorConfig-Core and copy that in. (This is even more fugly since it finds `libpcre.dylib` instead of `libpcre.a`, which means you have to make a more complicated transform…)

If anybody watching this has clever ideas (paging @xuhdev), I'd be happy to hear them.