Workaround incorrect sector sizes

This implements a vdev_sector_check(). It alters the detected sector
size of any device listed on a black list of drives known to lie about
their physical sector sizes.

This is based on sg_simple4.c from sg3_utils and "6931570 Add flash
devices' VID/PID to disk table to advertising 4K physical sector size"
from Open Solaris.

Signed-off-by: Richard Yao <ryao@gentoo.org>