[Coverity 1666128] Logically dead code in dvbsub.c

The indicated dead code may have performed some action; that action will never occur.

In alternative_CLUT: Code can never be reached because of a logical contradiction (CWE-561)

1101    p_clut->c_8b_entries = 0;
1102    while( i_processed_length < i_segment_length )
1103    {
1104        uint8_t y, cb, cr, t;
       dead_error_condition: The condition output_bit_depth == 1 cannot be true.
1105        if (output_bit_depth == DVBSUB_ST_BITDEPTH_10BIT)
1106        {
1107            // TODO: apply the palette locally to keep 10-bit values
      
CID 1666128: (#1 of 1): Logically dead code (DEADCODE)
dead_error_begin: Execution cannot reach this statement: y = bs_read(s, 10) >> 2;.
1108            y  = bs_read( s, 10 ) >> 2;

From 920f0add