error: Use error_report_err() where appropriate (again)

Same Coccinelle semantic patch as in commit 565f65d.

We now use the original error whole instead of just its message
obtained with error_get_pretty().  This avoids suppressing its hint
(see commit 50b7b00), but I don't think the errors touched in this
commit can come with hints.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1450452927-8346-3-git-send-email-armbru@redhat.com>

qemu-nbd.c

@@ -749,7 +749,7 @@ int main(int argc, char **argv)
     exp = nbd_export_new(blk, dev_offset, fd_size, nbdflags, nbd_export_closed,
                          &local_err);
     if (!exp) {
-        error_report("%s", error_get_pretty(local_err));
+        error_report_err(local_err);
         exit(EXIT_FAILURE);
     }