Reap STables in current run, not next one.

By then, the pointers are in a new tospace.
Bring coderef clone inline with other backends.

Or at least, the JVM one.
Take cuid from the QAST::Block.

Those in the generated bytecode must match up, otherwise fixups fail.
This fixes 56-role.t.
Merge branch 'master' of github.com:MoarVM/MoarVM into gcorch