Asynchronous Fsync: initial extraction of Async Fsync from HTC

Signed-off-by: Paul Reioux <reioux@gmail.com>

Conflicts:
	fs/sync.c
	include/linux/fs.h
fs: update sync
Revert "sync: allow async waits to be canceled"
This reverts commit https://github.com/gustavoss/android_kernel_samsung_smdk4412/commit/6fae2b63618f840a0122c0753dd2ba3181d50829
defconfig: update