Underscores in function pointer names causes invalid generated code

[Per Östlund]

This model fails to compile, because in the generated code a variable called _func_ptr is declared and assigned, but _func__ptr is instead used when trying to call the function.

function f
  output Real x := 3;
end f;

function test
  output Real x;
protected
  partial function FuncType
    output Real x;
  end FuncType;

  FuncType func_ptr := f;
algorithm
  x := func_ptr();
end test;