xcworkspace: remove GTL to speed-up compilation

VLC for iOS.xcworkspace/contents.xcworkspacedata

@@ -5,9 +5,6 @@
       location = "group:VLC for iOS.xcodeproj">
    </FileRef>
    <FileRef
-      location = "group:ImportedSources/GDrive/GTL.xcodeproj">
-   </FileRef>
-   <FileRef
       location = "group:ImportedSources/MediaLibraryKit/MediaLibraryKit.xcodeproj">
    </FileRef>
    <FileRef