Add ARM optimized versions of safe_address()

The function safe_address() uses inline assembler to detect
overflow in size/offset calculations, as detecting this in
plain C is a lot more work.
revert
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  revert
revert
Merge branch 'PHP-5.5'

* PHP-5.5:
  revert
  revert