This is not a bug, i386 support is dropped, gcc is configured to generate code for i486 and up. IIRC the kernel binaries for i386 do have a patch for emulation support for non-i386 instructions.
- Bug#231538: libc6: illegal instruction on a 386 Karolina Lindqvist
- Bug#231538: libc6: illegal instruction on a 386 Matthias Klose
- Bug#231538: libc6: illegal instruction on a 38... Matthias Klose
- Bug#231538: libc6: illegal instruction on ... Herbert Xu
- Bug#231538: libc6: illegal instruction... Karolina Lindqvist
- Bug#231538: libc6: illegal instru... Andreas Barth
- Bug#231538: libc6: illegal in... Karolina Lindqvist