vp9-resize: Fix an issue with external dynamic resize.
External dynamic resize with swapping width and height was not handled properly. Fix is to re-init loop-filter under certain condtions. Modify unittest to test this case. Without this change test will fail. Relates to: https://bugs.chromium.org/p/webm/issues/detail?id=1140 Change-Id: I7d81ca7fe0783b3bc103a52a7b7cf073a96be26e