Rewrite function definitions in the UFS/FFS code base with identifier lists.
The K&R style in UFS and other places in the tree's days are numbered
as this syntax is removed in C2x proposal N2432:
https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2432.pdf
Though running to nearly 6000 lines of diffs this update should cause
no functional change to the code.
Requested by: Warner Losh
MFC after: 2 weeks