Support building both Chisel and Scala libraries

_This_ is why I didn't support building Chisel libraries before: not
because I couldn't, but because that was how I was detecting that a
library should be build with Scala instead of Chisel.

This properly fixes the problem by checking the library's name: if it
ends in .jar then it's considered a Scala library, otherwise it's
considered a Scala library.
Add Chisel -d error message

Now if you forget to call Chisel with -d you won't just dereference a
NULL pointer :).
Support -{l,L}ARG in pscala{c,ld}

This is needed to work around an odd Ubuntu pkg-config behavior where
the output of pkg-config is sorted for some reason -- no idea why!