cpus: remove common cpu variants/extensions definition and simplify variant check.
Having common cpu variants/extensions has no real additional value since we are supporting
very various CPUs where minimal/standard/full have different meanings. Checking against
common variants/extensions has also cause more issues recently when adding new CPUs than
the additional value it was supported to provide.
So let's just simplify things: a CPU provide the supported variants and we just check
against that.
13 files changed: