Don't add libs to chisel.pc

These were actually getting added by pconfigure already.  It might be
best to add these to the pkg-config file and remove the hard-coded
string from pconfigure, but for now I think it's OK.
Use <chisel_emulator.h> instead of "emulator.h"

This is a two-in-one change: point to the global include (as we're now
installing Chisel properly), and point to the _correcet_ include (as
I've changed it to be Chisel-specific).