I installed the Arduino IDE 1.6.4, and used the "boards manager" to install the package for Arduino Due.
I am using c++11 in my project so i need to add the compiler.cpp.extra_flags=-std=gnu++11
like i did in the /Applications/Arduino.app/Contents/Java/hardware/arduino/platform.txt
file (i am on MacOSX).
It seems that arduino is ignoring that file and using a configuration coming from somewhere else.
Where is the downloaded package installed? Can it be configured?