Fix a typo in solver.cc
Fix a typo in solver.cc

Change-Id: I3f2e058e2d45c72eaa12129ff0b9366332ee87f5

kartikkumar/ceres-solver,entylop/ceres-solver,entylop/ceres-solver,kartikkumar/ceres-solver,stonier/ceres_solver,timfel/ceres-bin,entylop/ceres-solver,timfel/ceres-bin,timfel/ceres-bin,whuaegeanse/ceres-solver,kartikkumar/ceres-solver,DougFirErickson/ceres-solver,kartikkumar/ceres-solver,stonier/ceres_solver,ysonggit/ceres-solver,whuaegeanse/ceres-solver,DougFirErickson/ceres-solver,DougFirErickson/ceres-solver,ysonggit/ceres-solver,timfel/ceres-bin,stonier/ceres_solver,ysonggit/ceres-solver,ysonggit/ceres-solver,whuaegeanse/ceres-solver,DougFirErickson/ceres-solver,entylop/ceres-solver,whuaegeanse/ceres-solver,stonier/ceres_solver