Have ptest fail on failing tests again

This got broken in an update.  I guess I should have some ptest
tests... :).
Don't SEGV pbashc on missing files

I abort instead, which isn't much nicer!
Print valgrind error messages to console

This makes it a bit easier to debug test failures, which this time
turned out to be a valgrind bug!
Use pkg-config to find Chisel

I used to always be using the system Chisel at compile time, now I
properly discover a Chisel and build against it.