Add a sys.exit for merge layer in v2 layer converter file.
Add a sys.exit for merge layer in v2 layer converter file.

We haven't ported this yet, but would be nice to merge the rest of the changes.
Fail if someone uses this.

lwtnn/lwtnn,jwsmithers/lwtnn,lwtnn/lwtnn,jwsmithers/lwtnn,lwtnn/lwtnn,jwsmithers/lwtnn