adjust debugging code to print SMT var name comment as prefix

This code is disabled, but was intended to allow developers to print the Murphi
name of a variable as a following comment to the SMT symbol used. This is useful
for debugging subtle problems in the SMT translation. Following commit
5bb6144f, forall expressions used a second
variable of the form "s42_iteration". Because we append the "_iteration" text
this broke the debugging support here. I.e. with the debug flag enabled, this
would be printed as something like "s42 ; foo\n_iteration". We now print the
comment *preceding* the SMT variable instead of following, so this debugging
functionality should once again work.