Fix definition of cache_inode_dec_pin_ref to be a void function

Also document the 2nd closefile parameter.

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>
Fix callers of cache_inode_dec_pin_ref to use false/true instead of FALSE/TRUE

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>