Add common_magic member to struct riscv_info. Introduce is_riscv() helper. Change-Id: I1af05988ad869342ba5dc6d4d0ba0ec6a8bf7bc7 Signed-off-by: Tomas Vanek <vanekt@fbl.cz> Reviewed-on: https://review.openocd.org/c/openocd/+/6999 Tested-by: jenkins Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com> Reviewed-by: Tim Newsome <tim@sifive.com>