SECURITY UPDATE: use-after-free in ImagesToBlob() on multi-image writes
debian/patches/CVE-2026-93586.patch: add SyncBlobStream() to
magick/blob.c and call it after each WriteImage() in
magick/constitute.c and after the write in ImageToBlob() and
ImagesToBlob(), so the image list and image_info stop referencing
the buffer a previous frame's SetBlobExtent() reallocated