638 skip alignment checking block

[jberthold]

To solve #638 , there are several possibilities:

1. implement a pointer emulation which is aware of the underlying alignment: A pointer->usize cast should return an address which is aligned in the way that the pointer (possibly after an offset and casts to different pointer types) requires.
2. recognise the entire block responsible for the alignment check and rewrite it to a K sequence performing an equivalent alignment check.

This PR takes the first step for option 2, recognising (and for now skipping) the alignment-checking block as a whole.