Make sure we do not restart engines after disable Ponce

Right now we calling triton_restart_engines() when disabling Ponce.

We should make sure the following use case works fine:

User gets at early stage the input he wants to symbolize
After symbolizing there are trash functions he wants not to trace (he may lost the track of the symbolic state and not getting accurate results) so he disables Ponce
The previous state must have been kept
We should concretize all the registers because we won't know their value anymore
Later on he enables Ponce back and the state is kept so concolic execution keeps working

Right now en disabling Ponce we triton_restart_engines() so the 3rd item in the prev list is not enforced.

illera88 / Ponce