fs/dyn_sync_cntrl: dynamic sync control [1/2]

The dynamic sync control interface uses Android kernel's unique early
suspend / lat resume interface.

While screen is on, file sync is disabled
when screen is off, a file sync is called to flush all outstanding writes
and restore file sync operation as normal.

Signed-off-by: Paul Reioux <reioux@gmail.com>
Added build script.
Credits to laufersteppenwolf.