MKV: stop spamming about "unknown seekhead reference"

Seriously, HD logs have 12000 of lines of logs because of that... This is beyond ridiculous.

modules/demux/mkv/matroska_segment_parse.cpp

@@ -60,7 +60,9 @@ void matroska_segment_c::ParseSeekHead( KaxSeekHead *seekhead )
             EbmlId id = EbmlVoid::ClassInfos.GlobalId;
             int64_t i_pos = -1;
 
+#ifdef MKV_DEBUG
             msg_Dbg( &sys.demuxer, "|   |   + Seek" );
+#endif
             ep->Down();
             while( ( l = ep->Get() ) != NULL )
             {
@@ -121,8 +123,10 @@ void matroska_segment_c::ParseSeekHead( KaxSeekHead *seekhead )
                     msg_Dbg( &sys.demuxer, "|   - attachments at %"PRId64, i_pos );
                     LoadSeekHeadItem( KaxAttachments::ClassInfos, i_pos );
                 }
+#ifdef MKV_DEBUG
                 else
                     msg_Dbg( &sys.demuxer, "|   - unknown seekhead reference at %"PRId64, i_pos );
+#endif
             }
         }
         else

modules/demux/mkv/mkv.hpp

@@ -110,6 +110,8 @@ extern "C" {
 #   include <zlib.h>
 #endif
 
+#define MKV_DEBUG 0
+
 #define MATROSKA_COMPRESSION_NONE  -1
 #define MATROSKA_COMPRESSION_ZLIB   0
 #define MATROSKA_COMPRESSION_BLIB   1