Enable SSE2 on 32-bit Linux. For some reason it got disabled in commit 69a34042d2afe168a07da0ae1cd2df82b82b41da.

This fixes a problem with grip-samples on 32-bit Linux machines, where the simulation would return NaNs and the robot disappear. The problem was caused by the grip-samples being compiled with SSE2 and DART without.
Merge branch 'master' into sensory