upgrade g++ and clang before compiling under travis
upgrade g++ and clang before compiling under travis


Former-commit-id: 2b5b27a3c0da05b03633a5061b2dc8b2dda996a5
Former-commit-id: 8bce37adc39a94d6eabaa1ba736539194204a146
islog/leosac,islog/leosac,leosac/leosac,leosac/leosac,leosac/leosac,islog/leosac