question on buffer-file-coding-system

I just found that hexl is broken if you build XEmacs without FILE_CODING turned on - it attempts to take the value of the variable buffer-file-coding-system which is not defined if FILE_CODING is not enabled. I submitted a silly patch for this that uses (boundp buffer-file-coding-system) to determine whether this variable is defined. This seems like a kludge. I'm wondering if it might be better to ensure that buffer-file-coding-system is defined even if FILE_CODING is not present. This means that package lisp wouldn't have to be checking whether buffer-file-coding-system is bound. On the other hand, this wouldn't help for people with older XEmacs versions who update their packages. What is the right way to handle this? Check for boundp in Lisp code, or make sure the variable is defined even if FILE_CODING is not enabled? Or some other approach?