TCG memory leak with FreeDOS 'edit'

This bug has been copied automatically from: https://bugs.launchpad.net/qemu/+bug/1896298
Reported by 'Michael Slade' on 2020-09-18 :

qemu trunk as of today leaks memory FAST when freedos' edit is running.

To reproduce, download:

https://www.ibiblio.org/pub/micro/pc-
stuff/freedos/files/repositories/1.3/cdrom.iso

Then run:

$ qemu-system-i386 -cdrom cdrom.iso

select your language then select "return to DOS", then type

> edit

it will consume memory at ~10MB/s

This does NOT happen when adding -enable-kvm