osd/osd_types: fix pg_stat_t::dump for last_epoch_clean

Backport: cuttlefish
Signed-off-by: Sage Weil <sage@inktank.com>
(cherry picked from commit 69a55445439fce0dd6a3d32ff4bf436da42f1b11)
client: remove O_LAZY

The once-upon-a-time unique O_LAZY value I chose forever ago is now
O_NOATIME, which means that some clients are choosing relaxed
consistency without meaning to.

It is highly unlikely that a real O_LAZY will ever exist, and we can
select it in the ceph case with the ioctl or libcephfs call, so drop
any support for doing this via open(2) flags.

Update doc/lazy_posix.txt file re: lazy io.

Backport: cuttlefish
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
(cherry picked from commit 94afedf02d07ad4678222aa66289a74b87768810)