Convert remaining functions in vfs_subr.c from K&R prototypes to ANSI C
prototypes, as the majority of new functions added have been in this
style. Changing prototype style now results in gcc noticing that the
implementation of vn_pollrecord() has a 'short' argument instead of
'int' as prototyped in vnode.h, so correct that definition. In practice
this didn't matter as only poll flags in the lower 16 bits are used.

MFC after: 1 week