After #11427, `tvmc compile` wouldn't work for external codegens that
don't have a `Target` registered by `TVM_REGISTER_TARGET_KIND`. Such
external codegens can be expected to have no workspace pools and may not
always have a target associated as their implementation predates this
mechanism. While it is likely a `Target` is specified for all external
codegens in the future, we should still support external codegens
without an associated `Target` until this is enforced.
Co-authored-by: Chris Sidebottom <chris.sidebottom@arm.com>
Luke Hutton
759a648cd5