Force the std feature for log
Force the std feature for log

While trying to build this crate with the gecko feature rust complained
about us using `log::set_boxed_logger` because it requires the std feature
which was not explicitly set in that crate.

saneyuki/servo,KiChjang/servo,saneyuki/servo,nnethercote/servo,KiChjang/servo,KiChjang/servo,DominoTree/servo,paulrouget/servo,DominoTree/servo,splav/servo,nnethercote/servo,notriddle/servo,nnethercote/servo,notriddle/servo,larsbergstrom/servo,notriddle/servo,DominoTree/servo,splav/servo,paulrouget/servo,larsbergstrom/servo,splav/servo,larsbergstrom/servo,saneyuki/servo,larsbergstrom/servo,paulrouget/servo,DominoTree/servo,saneyuki/servo,paulrouget/servo,paulrouget/servo,larsbergstrom/servo,nnethercote/servo,KiChjang/servo,nnethercote/servo,saneyuki/servo,notriddle/servo,nnethercote/servo,DominoTree/servo,splav/servo,notriddle/servo,KiChjang/servo,saneyuki/servo,splav/servo,saneyuki/servo,DominoTree/servo,notriddle/servo,paulrouget/servo,paulrouget/servo,KiChjang/servo,nnethercote/servo,larsbergstrom/servo,DominoTree/servo,saneyuki/servo,nnethercote/servo,splav/servo,nnethercote/servo,DominoTree/servo,saneyuki/servo,KiChjang/servo,notriddle/servo,splav/servo,paulrouget/servo,notriddle/servo,DominoTree/servo,paulrouget/servo,notriddle/servo,nnethercote/servo,saneyuki/servo,KiChjang/servo,KiChjang/servo,paulrouget/servo,larsbergstrom/servo,larsbergstrom/servo,KiChjang/servo,splav/servo,notriddle/servo,larsbergstrom/servo,splav/servo,larsbergstrom/servo,DominoTree/servo,splav/servo