Also extended the optional VM supplied routines to include sim_vm_sprint_addr.
Simulators which provide sim_vm_fprint_addr should also provide
sim_vm_sprint_addr with sim_vm_fprint_addr reworked to leverage
sim_vm_sprint_addr internally. sim_vm_sprint_addr is currently only used by
sim_brk_message() which is an API which a simulator may choose to use if
it supports multiple breakpoint types,