Fix warnings in kauth/authclient.c

Fix warnings in kauth/authclient.c

 -- In ka_Authenticate, explicitly cast 'start' and 'end' to void*,
    since kawrap_ubik_Call takes all arguments as void*s

 -- Fix kawrap_ubik_Call to not be an old-style declaration

 -- Only ignore strict prototypes and implicit function declaration
    warnings

Reviewed-on: http://gerrit.openafs.org/597
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>