Add the print_insn pointer to the disassemble info structure. This is
to prepare for QOMification support, where a QOM CPU hook function will
be responsible for setting the print_insn() function. Add this function
to the existing struct to consolidate such that only the one struct
needs to be passed to the new QOM API.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>