Update source to SDL2 2.0.12

Edward Rudd

2020-05-02 03f8528315fa46c95991a34f3325d7b33ae5538c

 source/src/hidapi/ios/hid.m

@@ -282,6 +282,7 @@
      NSLog( @"connected peripheral: %@", peripheral );
      if ( [peripheral.name isEqualToString:@"SteamController"] )
      {
         self.nPendingPairs += 1;
         HIDBLEDevice *steamController = [[HIDBLEDevice alloc] initWithPeripheral:peripheral];
         [self.deviceMap setObject:steamController forKey:peripheral];
         [self.centralManager connectPeripheral:peripheral options:nil];