Add *_start and *_running methods to VM_COLLECT_USAGE_DETAILS API
I want to count how many VM instructions get executed for an arbitrary block of ruby code with
VM_COLLECT_USAGE_DETAILS enabled. However, the current API enables VM usage detail collection immediately and only exposes methods to turn collection off.
I've issued a PR to add more methods to the VM usage details API and to disable collection by default: https://github.com/ruby/ruby/pull/2258