cat: Check for lack of success rather than a specific failure.

MFC after: 3 days
Sponsored by: Klara, Inc.
Reviewed by: oshogbo
Differential Revision: https://reviews.freebsd.org/D45149

(cherry picked from commit c6f9df7064106a3b016c13ea3b9a930362b53089)

cat: Missed a couple.

MFC after: 3 days
Sponsored by: Klara, Inc.

(cherry picked from commit ad4f3bdf733c1a670021f4db378338f5aaedbfd8)