Squish more warnings in xstat

Squish more warnings in xstat

Use a correct prototype for a_ProbeHandler in xstat_cm_Init
Fix a printf warning
rx_getAllAddr and afs_cb_interface.addr disagree on the sign of addresses
afs_interface.addr is a [], which we then use & to get the address of. Fix
this to stop the compiler from sulking.

Reviewed-on: http://gerrit.openafs.org/http://gerrit.openafs.org/184
Tested-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>