RFA: ARM: Implement __builtin_trap

[Mike Stump]

On Sep 7, 2010, at 9:12 PM, Mark Mitchell wrote:
> This patch implements __builtin_trap for ARM.  The default, for
> architectures that do not provide a "trap" instruction, is to call
> abort.  Executing an invalid instruction is a faster, smaller way to
> crash.

Would be nice for arm to allocate (and document) some short sequence that will never be used in future ISA enhancements, as otherwise old binaries that should die, would then just do whatever new instruction was added.