Add libsdl2-mixer-2.0-0 to ubuntu-precise; resolves travis-ci/apt-package-whitelist#1561
Add libsdl2-mixer-2.0-0 to ubuntu-precise; resolves travis-ci/apt-package-whitelist#1561

Packages: libsdl2-mixer-2.0-0 libsdl2-mixer-dbg libsdl2-mixer-dev

travis-ci/apt-package-whitelist,travis-ci/apt-package-whitelist