dm thin: use bool rather than unsigned for flags in structures

Also, move 'err' member in dm_thin_new_mapping structure to eliminate 4
byte hole (reduces size from 88 bytes to 80).

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>

diff --cc drivers/md/dm-thin-metadata.h
Simple merge

diff --cc drivers/md/dm-thin.c
Simple merge