macosx: also round volume percents

This prevent cases in which the percent value is one smaller than the
previous adjusted value.

modules/gui/macosx/simple_prefs.m

@@ -538,7 +538,7 @@ static inline char * __config_GetLabel( vlc_object_t *p_this, const char *psz_na
         [o_audio_vol_sld setEnabled: YES];
 
         i = config_GetInt( p_intf, "volume" );
-        i = i * 200 / AOUT_VOLUME_MAX;
+        i = i * 200.0 / AOUT_VOLUME_MAX + 0.5;
         [o_audio_vol_sld setIntValue: i];
         [o_audio_vol_fld setIntValue: i];
     }
@@ -899,7 +899,7 @@ static inline void save_module_list( intf_thread_t * p_intf, id object, const ch
     {
         config_PutInt( p_intf, "audio", [o_audio_enable_ckb state] );
         if( [o_audio_vol_fld isEnabled] )
-            config_PutInt( p_intf, "volume", [o_audio_vol_fld intValue] * AOUT_VOLUME_MAX / 200 );
+            config_PutInt( p_intf, "volume", [o_audio_vol_fld intValue] * AOUT_VOLUME_MAX / 200.0 + 0.5 );
         config_PutInt( p_intf, "volume-save", [o_audio_autosavevol_yes_bcell state] );
         config_PutInt( p_intf, "spdif", [o_audio_spdif_ckb state] );