Retire WITHOUT_DEBUG flag, due to poor support in many ports and not being really necessary

[madpilot]

Summary

While building ports in a poudriere jail defining WITH_DEBUG I had the need to disable debug for specific ports failing to build due to requiring too much RAM for debugging build (llvm, for example).

I discovered that most ports who check for WITH_DEBUG are ignoring WITHOUT_DEBUG.

Also, the same intended effect of the WITHOUT_DEBUG flag can be obtained by using ".undef WITH_DEBUG" without requiring port Makefiles to have any special support.

Test Plan

If required an exp-run could be useful to make sure I did not break anything.

The patch does not modify the behavior of many ports having a DEBUG OPTION, bug not respecting WITH_DEBUG. A more complex patch is needed to fix that, but removing WITHOUT_DEBUG is a first small step in the right direction to fix that too.

[mat]

I think the WITHOUT_DEBUG knob should be removed instead.

[madpilot]

Added a simpler patch which removes all references to WITHOUT_DEBUG and adds a note to UPDATING to inform users of the change and suggests the supported way.

[mat]

This looks ok to me.