update google sparsehash to version 2.0.2

N/A

Change-Id: I86518723f25a88ce313626ee66642a97fdee9485
Signed-off-by: liuhuahang <liuhuahang@zerus.co>
Merge pull request #13 from project-zerus/patch-2

update google sparsehash to version 2.0.2