minor optimizations to FLAC__bitwriter_write_rice_signed_block()
minor optimizations to FLAC__bitwriter_write_rice_signed_block()

fredericgermain/flac,fredericgermain/flac,LordJZ/libflac,fredericgermain/flac,waitman/flac,LordJZ/libflac,Distrotech/flac,kode54/flac,fredericgermain/flac,LordJZ/libflac,Distrotech/flac,Distrotech/flac,kode54/flac,LordJZ/libflac,waitman/flac,kode54/flac,Distrotech/flac,waitman/flac,waitman/flac,waitman/flac,kode54/flac