OSV-2018-454 Use-of-uninitialized-value in fz_expand_indexed_pixmap

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5645 Crash type: Use-of-uninitialized-value Crash state: fzexpandindexedpixmap fzdecompimagefromstream compressedimagegetpixmap...