Watchdog Timers and Init Code

A change has been made to the start-up code: the code to
disable the watchdog timer has been removed.  The code was
in the start-up sequence because it was found that for some
large applications the watchdog timer would trigger whilst
the start-up was happening - ie before main() was reached.

The problem with the disabling code was that the address of
the watchdog timer was hard-coded in the instruction
sequence, which meant that it did not work on MCUs that
used a different address.  Rather than try to provide some
complicated, MCU specific, mechanism for disabling the timer
during start-up it was decided to simply remove the code
instead.  For most applications this should suffice.  If
however an application does need to disable the watchdog
timer during start-up, it can add this function to its code
base:

#include <msp430.h>

static void __attribute__((naked, section(".crt_0042"), used))
disable_watchdog (void)
{
  WDTCTL = WDTPW | WDTHOLD;
}

Note - this method can be used to insert *any* commands
into the start-up sequence, not just watchdog timer
disabling code.  Also if the number in .crt_0042 is
reduced, the code will execute earlier in the start-up
sequence.  If it is increased it will execute later in
the start-up sequence.