Optimise if/unless wrt OP_AND/OP_OR/OP_DOR. Also optimise OP_OR/OP_DOR chains.

Optimise if/unless wrt OP_AND/OP_OR/OP_DOR. Also optimise OP_OR/OP_DOR chains.

An OP_AND/OP_OR/OP_DOR in void context provides a short circuit
through ->op_other that can be used if AND/OR/DOR ops contained
within it jump out early. Use that short circuit.

Previously:

  $ ./perl -Ilib -MO=Concise -e 'if ($aa || $bb) {}'
  8  <@> leave[1 ref] vKP/REFC ->(end)
  1     <0> enter ->2
  2     <;> nextstate(main 3 -e:1) v:{ ->3
  -     <1> null vK/1 ->8
  6        <|> and(other->7) vK/1 ->8
  -           <1> null sK/1 ->6
  4              <|> or(other->5) sK/1 ->6              <-- Not optimised
  -                 <1> ex-rv2sv sK/1 ->4
  3                    <$> gvsv(*aa) s ->4
  -                 <1> ex-rv2sv sK/1 ->-
  5                    <$> gvsv(*bb) s ->6
  -           <@> scope vK ->-
  7              <0> stub v ->8

Now:

  $ ./perl -Ilib -MO=Concise -e 'if ($aa || $bb) {}'
  8  <@> leave[1 ref] vKP/REFC ->(end)
  1     <0> enter ->2
  2     <;> nextstate(main 3 -e:1) v:{ ->3
  -     <1> null vK/1 ->8
  6        <|> and(other->7) vK/1 ->8
  -           <1> null sK/1 ->6
  4              <|> or(other->5) sK/1 ->7               <-- Short circuited
  -                 <1> ex-rv2sv sK/1 ->4
  3                    <$> gvsv(*aa) s ->4
  -                 <1> ex-rv2sv sK/1 ->-
  5                    <$> gvsv(*bb) s ->6
  -           <@> scope vK ->-
  7              <0> stub v ->8