linux kernel lacks uintptr

linux kernel lacks uintptr

sadly only recent kernels include uintptr_t. change the cast to use unsigned
long

Change-Id: Ib69f7aa0f2d316c5ea8bdc960b15ee0f89f96250
Reviewed-on: http://gerrit.openafs.org/1059
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 165571947be770645900bb8d55ba7b6a3c58f8fd)
Reviewed-on: http://gerrit.openafs.org/1081