defs.h: introduce {opt,dispatch}_{word,klong}size

defs.h: introduce {opt,dispatch}_{word,klong}size

* defs.h (set_personality, current_personality, current_wordsize,
current_klongsize, max_addr, max_kaddr): Move upwards.
(opt_wordsize): New macro, calls the first or the second argument
depending on the word size.
(dispatch_wordsize): New macro, calls the first or the second function
with the rest of macro parameters as arguments depending on the word
size.
(opt_klongsize): New macro, calls the first or the second argument
depending on the kernel long size.
(dispatch_klongsize): New macro, calls the first or the second function
with the rest of macro parameters as arguments depending on the kernel
long size.