[avfoundation] Fix breaking changes (apidiff) (#2664)

src/AVFoundation/AVCompat.cs

@@ -68,6 +68,14 @@ namespace XamCore.AVFoundation {
 #endif
 
 #if !XAMCORE_4_0
+	partial class AVCaptureInputPort {
+
+		[Obsolete ("Valid instance of this type cannot be directly created.")]
+		public AVCaptureInputPort ()
+		{
+		}
+	}
+	
 	partial class AVAudioChannelLayout {
 
 		[Obsolete ("Valid instance of this type cannot be directly created.")]

src/avfoundation.cs

@@ -2834,7 +2834,7 @@ namespace XamCore.AVFoundation {
 
 #if !XAMCORE_4_0
 		[Obsolete ("Use 'GetMetadataForFormat' with enum values AVMetadataFormat.")]
-		[Wrap ("GetMetadataForFormat (new NSString (format))")]
+		[Wrap ("GetMetadataForFormat (new NSString (format))", IsVirtual = true)]
 		AVMetadataItem [] MetadataForFormat (string format);
 #endif
 		[Export ("metadataForFormat:")]