t/op/magic.t redirect stderr to /dev/null

This file calls ps(1), assuming that ps accepts the 'h' and 'hc'
options.  This is non-portable.  The comments in the code indicate that
these tests are optional; just skip them if the ps doesn't work.  The
problem is that noise gets generated on such platforms.  Simply redirect
stderr to /dev/null, suppressing any warnings.

Author: khwilliamson

t/op/magic.t

@@ -412,7 +412,8 @@ EOP
     # work (like if the system doesn't have a ps(1) for whatever
     # reason) just bail out gracefully.
     my $maybe_ps = sub {
-        my ($cmd) = @_;
+        my ($cmd) = @_ ;
+        $cmd .= " 2>$::devnull";
         local ($?, $!);
 
         no warnings;