Add all targets to mf->targets

This was probably just an omission.
Prevent chisel_quirks() from duplicating targets

Chisel has a quirks method that generates some additional targets.  As
there's no specification for what a quirks method should do,
pconfigure doesn't do any checking at all to ensure that it hasn't
already been run.  THis adds a check into the quirks method to avoid
duplicating targets.