x86: h264: Don't use redzone in AVX h264_deblock on Win64

This fixes crashes in chromium on win64 on machines with AVX
(crashes that apparently aren't triggered by fate).

Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit 311443f6c7eb230276e320f2d30a5d729cf32b76)

Signed-off-by: Martin Storsjö <martin@martin.st>