Fix JSON tracing for sub-calls.

[tomusdrw]

CC @holiman @cdetrio

[arkpar]

Does this change instructions trace to be show pre-execution data, rather than post-execution?

[tomusdrw]

The state is still pre-execution (gas used, memory, stack, etc) although the trace should be printed only on successful gas calculation.
Because of that we were printing CREATE/CALL/DELEGATECALL instruction after all sub-call traces which looked weird.

Before:

..create initialization (depth: 1)
PUSH (depth: 2)
CREATE (depth: 1) // create executed

Now:

..create initialization (depth: 1)
CREATE (depth: 1) // create executed
PUSH (depth: 2)

[holiman]

Looks correct to me