MSP430: Fix message in sbrk.c printing binary character

The call to write() in sbrk.c was using the wrong value for the length
argument, causing the NUL terminating character of the string to be
printed.

libgloss/msp430/sbrk.c

@@ -24,8 +24,8 @@ _sbrk (int adj)
 
   if (heap + adj > sp)
     {
-#define MESSAGE "Heap and stack collision\n"
-      write (1, MESSAGE, sizeof MESSAGE);
+      const char * const msg = "Heap and stack collision\n";
+      write (1, msg, sizeof (msg) - 1);
       abort ();
     }