MFC r363439:

Correct a type-mismatch between xdr_long and the variable "bad".

Way back in r28911 (August 1997, CVS rev 1.22) we imported a NetBSD
information leak fix via OpenBSD. Unfortunatly we failed to track the
followup commit that fixed the type of the error code. Apply the change
from int to long now.

Reviewed by: emaste
Reported by: CHERI
Obtained from: CheriBSD
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D25779