bug#13409: [patch] make some error messages clearer

[Paul Eggert]

On 01/10/13 11:20, Benno Schulenberg wrote:
> Several error messages in some of the utilities say things
> like "reading %s".  They sound like progress messages, and
> translators might be tempted to translate them as if they
> said "busy reading %s"

-          error (0, errno, _("reading %s"), quote (src_name));
+          error (0, errno, _("error reading %s"), quote (src_name));

Surely a translator who read the message in context will see
that it's an error message, since 'error' is being called.

I'm not sure we want to change the wording, but if we do change
it I suggest "cannot read %s" rather than "error reading %s",
as the gerunds make the wording less clear.