Add integration test for garbled stacktraces

[Javier Honduvilla Coto]

rbperf/src/rbperf.rs

Line 436 in 28e2f52

 if method_name.is_err() { 

p ((struct RString)(*((rb_control_frame_t*) (ruby_current_vm_ptr->ractor->main_thread->ec->vm_stack + ruby_current_vm_ptr->ractor->main_thread->ec->vm_stack_size) - 2).iseq.body.location.label)).as.heap.ptr

set *(0x7fd016296c42+2) = 0xf
set {char [10]} 0x7fd016296c42 = 0xf