.travis.yml: Link the gcc/g++ binaries to the newest version.
.travis.yml: Link the gcc/g++ binaries to the newest version.

nanshe-org/rank_filter,DudLab/rank_filter,jakirkham/rank_filter,DudLab/rank_filter,jakirkham/rank_filter,jakirkham/rank_filter,nanshe-org/rank_filter,DudLab/rank_filter,nanshe-org/rank_filter