Update c->dst.bytes in decode instruction instead of instruction
itself.  It's needed because if c->dst.bytes is equal to 0, the
instruction is not emulated.
Signed-off-by: NGuillaume Thouvenin <guillaume.thouvenin@ext.bull.net>
Signed-off-by: NLaurent Vivier <laurent.vivier@bull.net>
Signed-off-by: NAvi Kivity <avi@qumranet.com>