OSV-2026-868 Use-of-uninitialized-value in vp8_regular_quantize_b_sse4_1

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=520318421 Crash type: Use-of-uninitialized-value Crash state: vp8regularquantizebsse41 macroblockyrd vp8rdpickintramode...