Small cleanups in audioproperties.cpp.
Small cleanups in audioproperties.cpp.

black78/taglib,pbhd/taglib,black78/taglib,TsudaKageyu/taglib,black78/taglib,TsudaKageyu/taglib,Distrotech/taglib,videolabs/taglib,TsudaKageyu/taglib,taglib/taglib,dlz1123/taglib,Distrotech/taglib,dlz1123/taglib,i80and/taglib,i80and/taglib,pbhd/taglib,Distrotech/taglib,videolabs/taglib,i80and/taglib,pbhd/taglib,taglib/taglib,dlz1123/taglib,taglib/taglib,videolabs/taglib