libbb: fix parsing of "10101010" date/time form

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
libbb: if opening /dev/loopN returns ENXIO, don't try N++.

function                                             old     new   delta
set_loop                                             639     635      -4

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>