Turn on link time optimisations by default

For Yocto based embedded linux users, performance optimization and enhancement features should be on by default instead of manually finding and turning them on.Otherwise customers may not discover the feature thus leading to solutions that perform worse than they should.

This given that there are no side effects for interoperability with specific hardware's, deployment, debugging, profiling or testing. If such side effects are discovered, instead of turning the feature on by default we need to find a way to better promote it at the relevant (final) stages of the customer project.