No functionality changed. Clean up only.
Make early init code (Reset_Handler) use the existing irq stack
rather than the hard-coded one.
Remove (now) unused references to the hard-coded stack.
Removed the link-time check for a minimal task stack in RAM since
FreeRTOS allocates user stacks from the heap which is already reserved
in the .bss section (as symbol xHeap).
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@756 ebee16cc-31ac-478f-84a7-5cbb03baadba