uudecode: correct error message

PR: 153276
Reported by: David Brennan

(cherry picked from commit 9f3203c003144a4ef6309435036f985afe549ff0)

uudecode: add missing test files to Makefile

(cherry picked from commit 1b3af110bcd522a077f01350b6a51b3ffe434393)

uudecode: use SRCDIR in the regression test

(cherry picked from commit f5138631fb6f9dc73d696560caa006f3df714b9a)

uudecode: move the new uudecode test from uuencode/ to uudecode/

I don't know how that happened.

(cherry picked from commit ae6aa2d43daa6276dd18dc974a1c5b7c15264615)