Made a new copy of Marlin, replaced the configuration.h file with yours and it compiles with no errors with Arduino 1.6.8. I haven't upgraded to 1.6.9 yet. Running Win10x64 with UAC totally off.
I use Documents/Arduino/printername/MarlinRC6/ with the github files in it. The printername is the name of the 3d printer, since I have more than one.
I use Documents/Arduino/printername/MarlinRC6/ with the github files in it. The printername is the name of the 3d printer, since I have more than one.