Fix g++-4.8 compile errors.
Fix g++-4.8 compile errors.

efcs/benchmark,google/benchmark,codygray/benchmark,mockingbirdnest/benchmark,everbase/benchmark,mockingbirdnest/benchmark,everbase/benchmark,google/benchmark,disconnect3d/benchmark,codygray/benchmark,efcs/benchmark,disconnect3d/benchmark,codygray/benchmark,everbase/benchmark,efcs/benchmark,mockingbirdnest/benchmark,everbase/benchmark,google/benchmark,efcs/benchmark,codygray/benchmark,disconnect3d/benchmark,disconnect3d/benchmark,mockingbirdnest/benchmark