OpenColorIO vulnerable to stack buffer overflow via unbounded `sscanf %s` in Spi3D (.spi3d) LUT parser

OpenColorIO is a color management framework for visual effects and animation. Prior to version 2.5.2, `FileFormatSpi3D.cpp:163` uses `sscanf` with `%s` into 64-byte stack buffers when parsing LUT data lines. Input comes from `lineBuffer[4096]`, so a crafted .spi3d file can overflow by ~4000 bytes on non-Windows. Version 2.5.2 fixes the issue.