[RFA/libgloss/arm] Handle zero heap base from semihosting

[Nick Clifton]

Hi Matthew,

   Thanks for posting this patch.  Sorry for the delay in reviewing - I 
have been off on vacation.

   Anyway the patch is fine and I have checked it in.

Cheers
   Nick

libgloss/ChangeLog
2011-09-29  Matthew Gretton-Dann  <matthew.gretton-dann@arm.com>

	* arm/crt0.s: Support 0 heap base response from HeapInfo syscall.