- Fix spillslot coalescing timer not being displayed

use custom value_interfere function in verifiers (which is slower but doesn't rely on correct liveness information), fix memperm creation

- new spillslot verifier (doesn't catch all errors at the moment, because lifeness analysis ignores non-schedule nodes)

- No need to set strange spillcontexts on spills anymore
- Spillcontexts are now assigned and coalesced in a separate pass after spilling/register allocation of all register classes
- There might be cases where the new code inserts memcopies, these are not implemented in the ia32 backend yet