Decrease panic handling code for assigner target

[aleasims]

First step was done in:

• [ ] #35

Actually we can go forward and completely replace code in panic implementation for intrinsics::abort() as it is done in panic_fmt.

This will reduce panic function to something like:

define void @panic(...) {
start:
  tail call void @llvm.trap()
  unreachable
}

This will not require assigner to interpret useless instructions in case of panic.