ebml: Constify getters.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/demux/mkv/Ebml_parser.cpp

@@ -116,7 +116,7 @@ void EbmlParser::Keep( void )
     mb_keep = true;
 }
 
-int EbmlParser::GetLevel( void )
+int EbmlParser::GetLevel( void ) const
 {
     return mi_user_level;
 }
@@ -193,7 +193,7 @@ EbmlElement *EbmlParser::Get( void )
     return m_el[mi_level];
 }
 
-bool EbmlParser::IsTopPresent( EbmlElement *el )
+bool EbmlParser::IsTopPresent( EbmlElement *el ) const
 {
     for( int i = 0; i < mi_level; i++ )
     {

modules/demux/mkv/Ebml_parser.hpp

@@ -43,10 +43,10 @@ class EbmlParser
     void        Keep( void );
     EbmlElement *UnGet( uint64 i_block_pos, uint64 i_cluster_pos );
 
-    int  GetLevel( void );
+    int  GetLevel( void ) const;
 
     /* Is the provided element presents in our upper elements */
-    bool IsTopPresent( EbmlElement * );
+    bool IsTopPresent( EbmlElement * ) const;
 
   private:
     EbmlStream  *m_es;