f2fs-tools: release 1.6.0
f2fs-tools: release 1.6.0

This version introduces defrag.f2fs newly, and some major bug fixes too.

Change-Id: I3e5a918d97b95bd9e16e22b3ccaae9d90c55f5aa
Signed-off-by: Jaegeuk Kim <71255387a32c360dfbe6dfb7aaeb123bf1dc8cb6@kernel.org>

TeamTwisted/android_external_f2fs-tools,TeamTwisted/android_external_f2fs-tools