macosx: Implement row for library item in shows data source

Signed-off-by: Claudio Cambra <developer@claudiocambra.com>

modules/gui/macosx/library/video-library/VLCLibraryShowsDataSource.m

@@ -127,4 +127,12 @@
     return nil;
 }
 
+- (NSInteger)rowForLibraryItem:(id<VLCMediaLibraryItemProtocol>)libraryItem
+{
+    if (libraryItem == nil) {
+        return NSNotFound;
+    }
+    return [self indexOfMediaItem:libraryItem.libraryID inArray:self.showsArray];
+}
+
 @end