I was actually getting a totally different error before, you can read about it here (and many posts after this one):
I'm building from the same code you are if you cloned my "watchdog_timer_fix" code... so it must be a difference in how our systems are set up.
My path is as follows:
C:\Program Files\GNU Tools ARM Embedded\4.7 2013q2\bin;C:\Program Files\GNU Tools ARM Embedded\4.7 2013q2\arm-none-eabi\include;C:\Program Files\GNU Tools ARM Embedded\4.7 2013q2\lib\gcc\arm-none-eabi\4.7.4\include;C:\Program Files\GnuWin32\bin;C:\Spark\dfu-util-0.7