busybox

dmesg: add -r option to print raw format even when FEATURE_DMESG_PRETTY is enabled

Similar to the "big" util-linux version. For !DMESG_PRETTY, the option is accepted
(but ignored) as well, for compatibility reasons.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>