Ignore selinux/android.h

Signed-off-by: David Greaves <david.greaves@jollamobile.com>
Original split_bootimg.pl from http://www.enck.org/tools/split_bootimg_pl.txt

Signed-off-by: David Greaves <david.greaves@jollamobile.com>
Provide command line to use mkbootimg to recreate the img file using suitable offsets

Signed-off-by: David Greaves <david.greaves@jollamobile.com>