Broken makefile dependency between `install` and `.pc` targets

This may be a kmkf issue.

`bmake -r install` fails if the `${BUILD}/pc/{libfsm,libre}.pc` files are missing. Running `bmake -r build/pc/libfsm.pc` and `bmake -r build/pc/libre.pc` and then `bmake -r install` works, but the install target should depend on them.