AVR Library

Well if you don't mind asking a dumb question then I don't mind either.
Why are you downloading the AVR library. I have been running every kind of arduino program for over six months and have never had to do that. What is the point of that ?

http://www.nongnu.org/avr-libc/user-manual/group__avr__watchdog.html

http://tushev.org/articles/arduino/item/46-arduino-and-watchdog-timer