Messages: missing const, fix Qt4 warning

include/vlc_messages.h

@@ -118,8 +118,8 @@ VLC_EXPORT( void, msg_Unsubscribe, ( msg_subscription_t * ) );
 /* Enable or disable a certain object debug messages */
 #define msg_EnableObjectPrinting(a,b) __msg_EnableObjectPrinting(VLC_OBJECT(a),b)
 #define msg_DisableObjectPrinting(a,b) __msg_DisableObjectPrinting(VLC_OBJECT(a),b)
-VLC_EXPORT( void, __msg_EnableObjectPrinting, ( vlc_object_t *, char * psz_object ) );
-VLC_EXPORT( void, __msg_DisableObjectPrinting, ( vlc_object_t *, char * psz_object ) );
+VLC_EXPORT( void, __msg_EnableObjectPrinting, ( vlc_object_t *, const char * psz_object ) );
+VLC_EXPORT( void, __msg_DisableObjectPrinting, ( vlc_object_t *, const char * psz_object ) );
 
 /**
  * @}

src/misc/messages.c

@@ -133,7 +133,7 @@ void msg_Create (libvlc_int_t *p_libvlc)
 static void const * kObjectPrintingEnabled = &kObjectPrintingEnabled;
 static void const * kObjectPrintingDisabled = &kObjectPrintingDisabled;
 
-void __msg_EnableObjectPrinting (vlc_object_t *p_this, char * psz_object)
+void __msg_EnableObjectPrinting (vlc_object_t *p_this, const char * psz_object)
 {
     libvlc_priv_t *priv = libvlc_priv (p_this->p_libvlc);
     vlc_rwlock_wrlock( &QUEUE.lock );
@@ -144,7 +144,7 @@ void __msg_EnableObjectPrinting (vlc_object_t *p_this, char * psz_object)
     vlc_rwlock_unlock( &QUEUE.lock );
 }
 
-void __msg_DisableObjectPrinting (vlc_object_t *p_this, char * psz_object)
+void __msg_DisableObjectPrinting (vlc_object_t *p_this, const char * psz_object)
 {
     libvlc_priv_t *priv = libvlc_priv (p_this->p_libvlc);
     vlc_rwlock_wrlock( &QUEUE.lock );