f2fs/fscrypt: catch up to v4.12

Applied f2fs-related patches only, and tried to exclude other layers' changes.

- fs/f2fs

c6b1e36c Merge branch 'for-4.13/block' of git://git.kernel.dk/linux-block
81e3e044 Merge tag 'uuid-for-4.13' of git://git.infradead.org/users/hch/uuid
fdd050b5 Merge branch 'uuid-types' of bombadil.infradead.org:public_git/uuid into nvme-base
4e4cbee9 block: switch bios to blk_status_t
d41519a6 crypto: Work around deallocated stack frame reference gcc bug on sparc.
85787090 fs: switch ->s_uuid to uuid_t
bf5f8946 Merge branch 'akpm' (patches from Andrew)
48fbfe50 fs: f2fs: use ktime_get_real_seconds for sit_info times
a7c3e901 mm: introduce kv[mz]alloc helpers
70ef8f0d Merge tag 'for-f2fs-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
...

- fs/crypto/

4e4cbee9 block: switch bios to blk_status_t
17159420 fscrypt: introduce helper function for filename matching
6b06cdee fscrypt: avoid collisions when presenting long encrypted filenames
272f98f6 fscrypt: fix context consistency check when key(s) unavailable
9c8268de fscrypt: Move key structure and constants to uapi
cd39e4ba fscrypt: remove unnecessary checks for NULL operations
a643f905 Merge tag 'fscrypt-for-linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt


...

- fs/ext4/
: Applied fscrypt-related changes only.

Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>