Fix downsize on error before first frame

Retry with a lower definition if MediaCodec fails before the first
frame, not the first packet.

In practice, the first packet is a config packet without any frame, and
MediaCodec might fail just after.

Refs 2eb6fe7d81
Refs #2963 <https://github.com/Genymobile/scrcpy/issues/2963>

server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java

@@ -159,8 +159,11 @@ public class ScreenEncoder implements Device.RotationListener {
                     }
 
                     IO.writeFully(fd, codecBuffer);
+                    if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) == 0) {
+                        // If this is not a config packet, then it contains a frame
                         firstFrameSent = true;
                     }
+                }
             } finally {
                 if (outputBufferId >= 0) {
                     codec.releaseOutputBuffer(outputBufferId, false);