[tex-live] portability fixes for luatex

[Akira Kakuto]

Dear TL developers,

> that's a good point, but i cannot update the compiler (it's an old AIX
> 4.3 system with VAC 5 compiler). if the fixes don't reduce readability
> of the code, i'd like to get them applied.
> 
> plus, there are a few other changes in the patch, not related to
> variable declarations.
> 
>  PM> (I'm not a texlive developer, so this is just my personal opinion.)

I'm also using an old compiler incompatible with C99.
So I have to rewrite declarations in several cases.
I cannot insist but I'm glad if developers kindly use
old-fashioned delcarations.

Thanks,
Akira