VM: Added a comment back that was accidentally removed in the last commit

src/nasal_vm.cpp

@@ -674,6 +674,7 @@ void vm::run(const codegen& gen,
         imm.push_back(i.num);
     }
     CHECK_INTERRUPT;
+    // goto the first operand
     goto *code[ctx.pc];
 #else
     std::vector<nasal_vm_func> code;