I've done this in the past with no problems, following the instructions here:
But, this time, with v1.8.2, its not working - printf is still undefined when I do a build.
What's the trick? Is there a missing step, or something that has changed in v1.8.2? Worked find when I did it to the Due package, but is not working for the AVR package under the IDE install directory.
The path to the Print.h I edited was: