Enable SSE3 on MacOS, because -fast does not do it.
Enable SSE3 on MacOS, because -fast does not do it.

Change-Id: Ic0e29c36bf53a0bd91d2e1b6f79501481a89345b

stonier/ceres_solver,kartikkumar/ceres-solver,kartikkumar/ceres-solver,jmwalls/ceres-solver-fork,ikoruk/ceres-solver,techoe/ceres-solver,jmwalls/ceres-solver-fork,vedanshu95/ceres-solver,caomw/ceres-solver,vedanshu95/ceres-solver,pritasam/ceres-solver,stonier/ceres_solver,ikoruk/ceres-solver,caomw/ceres-solver,vedanshu95/ceres-solver,DougFirErickson/ceres-solver,ysonggit/ceres-solver,ikoruk/ceres-solver,pritasam/ceres-solver,caomw/ceres-solver,whuaegeanse/ceres-solver,arnaudgelas/ceres-solver,entylop/ceres-solver,ikoruk/ceres-solver,whuaegeanse/ceres-solver,pritasam/ceres-solver,techoe/ceres-solver,timfel/ceres-bin,kartikkumar/ceres-solver,stonier/ceres_solver,kartikkumar/ceres-solver,ysonggit/ceres-solver,timfel/ceres-bin,whuaegeanse/ceres-solver,jmwalls/ceres-solver-fork,arnaudgelas/ceres-solver,jmwalls/ceres-solver-fork,DougFirErickson/ceres-solver,entylop/ceres-solver,timfel/ceres-bin,ysonggit/ceres-solver,stonier/ceres_solver,ikoruk/ceres-solver,ysonggit/ceres-solver,timfel/ceres-bin,DougFirErickson/ceres-solver,techoe/ceres-solver,arnaudgelas/ceres-solver,entylop/ceres-solver,whuaegeanse/ceres-solver,DougFirErickson/ceres-solver,entylop/ceres-solver