Sometimes Avast can enable VT-x if it's disabled in BIOS, but usually it's not possible. VT-x is also not required on 32-bit OSes (except Win8+). Avast detects Hyper-V (or hypervisor for Android development) and then I think Avast doesn't use VT-x. There's also a technology called nested virtualization which allows you to have multiple hypervisors, but it's only supported on newer HW and it's quite slow.