SECURITY UPDATE: Integer overflow in the DIB coder leading to an
out-of-bounds read or write
debian/patches/CVE-2026-28693.patch: guard the columns/bits_per_pixel
and bytes_per_line/rows products with HeapOverflowSanityCheck() in
ReadDIBImage() and WriteDIBImage() in coders/dib.c, and add the same
guard to WriteBMPImage() in coders/bmp.c