Bug reported in #3305 has been reintroduced in master and https://github.com/cisco/openh264/tree/v2.2.0

Offending commit: dc17cee

Easy way to test:

1. Compile FreeRDP from https://github.com/FreeRDP/FreeRDP/tree/master with cmake -GNinja -DWITH_OPENH264=ON
2. Connect to some windows RDP server with xfreerdp /v:someserver (AVC mode enabled)
3. Create a selection rectangle with a mouse left click
4. Release the rectangle
5. See that the rectangle is (in part) still visible

To verify the stream can be decoded properly:

1. Compile FreeRDP from https://github.com/FreeRDP/FreeRDP/tree/master with cmake -GNinja -DWITH_FFMPEG=ON
2. Retry above