clash+parenthesis issues in the lustre generated code)

The  parenthesis  issues  were  occuring (sometimes)  in  the  lustre
generated code,  for 'pre', '#,'  'nor', and 'current'. A  issue with
int2real and real2int was fixed too.

fix: some issues in the lustre backend wrt =current=

The rationale is to allow the use of extern types, such as int8.

(and a --2smv one that is not finish)

https://www.cyber-neurones.org/2022/09/ubuntu-22-04-1-gcc-11-fcommon-issue-multiple-definition-of/

nb: still does not work for nested iterators

I think it is  safe to suppose that the node is on  the base clock in
this case.

The dependency on the clock was lost when the enum is translated into
an integer (because some expression were still refering to the enum type).

The fix was to index VarMap.t by string instead of Soc.var_expr in ActionsDeps.