Avoid searching the same area twice in MPEG::File::previousFrameOffset().
Avoid searching the same area twice in MPEG::File::previousFrameOffset().

black78/taglib,black78/taglib,TsudaKageyu/taglib,black78/taglib,taglib/taglib,TsudaKageyu/taglib,taglib/taglib,TsudaKageyu/taglib,taglib/taglib