Merge commit '6d93307f'

* commit '6d93307f':
  mpeg12: check scantable indices in all decode_block functions

Benchmarks

Before:
1878 decicycles in mpeg2_decode_block_non_intra, 8388487 runs, 121 skips
1700 decicycles in mpeg2_decode_block_intra, 4194239 runs, 65 skips
1808 decicycles in mpeg2_fast_decode_block_non_intra, 8388492 runs, 116 skips
1669 decicycles in mpeg2_fast_decode_block_intra, 4194248 runs, 56 skips
--
2056 decicycles in mpeg1_decode_block_inter, 65535 runs, 1 skips
2346 decicycles in mpeg1_decode_block_intra, 32768 runs, 0 skips
2011 decicycles in mpeg1_fast_decode_block_inter, 65533 runs, 3 skips
----------------
After:
1858 decicycles in mpeg2_decode_block_non_intra, 8388490 runs, 118 skips
1691 decicycles in mpeg2_decode_block_intra, 4194233 runs, 71 skips
1823 decicycles in mpeg2_fast_decode_block_non_intra, 8388493 runs, 115 skips
1681 decicycles in mpeg2_fast_decode_block_intra, 4194238 runs, 66 skips
--
2010 decicycles in mpeg1_decode_block_inter, 65535 runs, 1 skips
2322 decicycles in mpeg1_decode_block_intra, 32766 runs, 2 skips
1995 decicycles in mpeg1_fast_decode_block_inter, 65535 runs, 1 skips

All benchmarks are the best scores of several runs
Merged-by: Michael Niedermayer <michaelni@gmx.at>