VLCMediaPlayer and VLCMediaListPlayer: use DISPATCH_QUEUE_SERIAL instead of DISPATCH_QUEUE_SERIAL_WITH_AUTORELEASE_POOL to support < iOS10

(cherry picked from commit a7d189abb8f60f932c653a9699b1d50390af154b)
Signed-off-by: Felix Paul Kühne <felix@feepk.net>

Sources/VLCMediaDiscoverer.m

@@ -93,7 +93,7 @@ NSString *const VLCMediaDiscovererCategory = @"VLCMediaDiscovererCategory";
     if (self = [super init]) {
         _localizedName = nil;
         _discoveredMedia = nil;
-        _libVLCBackgroundQueue = dispatch_queue_create("libvlcQueue", DISPATCH_QUEUE_SERIAL_WITH_AUTORELEASE_POOL);
+        _libVLCBackgroundQueue = dispatch_queue_create("libvlcQueue", DISPATCH_QUEUE_SERIAL);
 
         if (libraryInstance != nil) {
             _privateLibrary = libraryInstance;

Sources/VLCMediaListPlayer.m

@@ -46,7 +46,7 @@
 - (instancetype)initWithOptions:(NSArray *)options andDrawable:(id)drawable
 {
     if (self = [super init]) {
-        _libVLCBackgroundQueue = dispatch_queue_create("libvlcQueue", DISPATCH_QUEUE_SERIAL_WITH_AUTORELEASE_POOL);
+        _libVLCBackgroundQueue = dispatch_queue_create("libvlcQueue", DISPATCH_QUEUE_SERIAL);
 
         VLCLibrary *library;
         if (options != nil) {

Sources/VLCMediaPlayer.m

@@ -1373,7 +1373,7 @@ static void HandleMediaPlayerSnapshot(const libvlc_event_t * event, void * self)
 - (dispatch_queue_t)libVLCBackgroundQueue
 {
     if (!_libVLCBackgroundQueue) {
-        _libVLCBackgroundQueue = dispatch_queue_create("libvlcQueue", DISPATCH_QUEUE_SERIAL_WITH_AUTORELEASE_POOL);
+        _libVLCBackgroundQueue = dispatch_queue_create("libvlcQueue", DISPATCH_QUEUE_SERIAL);
     }
     return  _libVLCBackgroundQueue;
 }