Make sure we do not restart engines after disable Ponce

[illera88]

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]

we should add documentation about this too