Make crash reporting more robust

As noted in https://github.com/openjdk/jdk/pull/8736 we should be using Safefetch in our crash reporting to make it more robust.

Other feedback is to:
- use a better name instead of "os::print_tos_pc"
- rename "os::print_context" => "os::print_registers" - Because that's the only thing it does. All other context printing has moved to print_tos_pc.
- rename "os::print_register_info" => "os::print_registers_detailed" (alt. print_registers_locations)