The function vmem_qcache_reap() and global variables 'needfree',
'desfree', and 'lotsfree' are all used in the upstream. While
these variables have no meaning under Linux they're being defined
as 0's to avoid needing to make additional changes to the ARC code.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>