Bug fixes:

* Use correct offset emitting memcpy instructions that target a non-zero offset.
* Clobber the buffer passed to 'stat' despite special handling for that call.
* Always count memcpy as a pending load if its context is disabled.
* Don't transpose attributes down one parameter when cloning functions.
Emit memcpy from a large constant as a residual memcpy instead of a store of a composite type, which ends up as a long sequence of i8 stores at least on Dragonegg 3.2.