sysstat: fix hash

Fix brainfail: mixed hash from dev and stable versions.
Fixes:
http://autobuild.buildroot.net/results/bdc/bdce55b88a4aaff82ce0a492a0a4f49ab5b9031b/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>