The SEGV happens because the -list-thread-groups --available command
triggers a windows_nat_target::xfer_partial call for a TARGET_OBJECT_OSDATA
object. Until a program is being debugged, the target_ops layer that
gets the call is the Windows "native" layer. Except for a couple of
specific objects (TARGET_OBJECT_MEMORY and TARGET_OBJECT_LIBRARIES),
this layer's xfer_partial method delegates the xfer of other objects
to the target beneath: