tests: write skip explanation from perl scripts also to outer stderr

* tests/CuSkip.pm (skip): New file/module/function, to help
the perl test scripts "skip" a test consistently, emitting
a diagnostic both into the log file and into the outermost
stderr stream that is more likely to be seen by a human.
* tests/check.mk (TESTS_ENVIRONMENT): Add -MCuSkip.
* tests/misc/date-next-dow: Use CuSkip::skip in place of warn+exit-77.
* tests/misc/tty-eof: Likewise.
* tests/misc/uniq: Likewise.
* tests/rm/fail-eperm: Likewise.
* tests/misc/md5sum-newline: Likewise.  Also, s/program_name/ME/.
* tests/misc/ls-misc (setuid_setup, main): Likewise.
* tests/misc/pwd-long: Likewise, and add -I"$abs_srcdir" -MCuSkip
to the $PERL invocation command.
Inspired by a request from Bruno Haible regarding misc/tty-eof:
http://debbugs.gnu.org/8570

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/misc/tty-eof b/tests/misc/tty-eof
index 14910dcfc..23cb4d564 100755
--- a/tests/misc/tty-eof
+++ b/tests/misc/tty-eof
@@ -25,8 +25,8 @@ use strict;
 # Some older versions of Expect.pm (e.g. 1.07) lack the log_user method,
 # so check for that, too.
 eval { require Expect; Expect->require_version('1.11') };
-$@ and (warn "$ME: this script requires Perl's Expect package >=1.11\n"),
-  exit 77;
+$@
+  and CuSkip::skip "$ME: this script requires Perl's Expect package >=1.11\n";
 
 {
   my $fail = 0;