fix look up of c header files
fix look up of c header files

uucidl/pre.transducers-in-c,uucidl/exp.cpp-explorations,uucidl/exp.transducers-in-c,uucidl/pre.transducers-in-c,uucidl/exp.transducers-in-c,uucidl/pre.transducers-in-c,uucidl/exp.transducers-in-c,uucidl/exp.cpp-explorations