Avoid breaking ValueMap iterators by using aux data structure during Remap
2 bugfixes:

* A silly out-of-bounds write (wrong induction variable)
* Don't redirect branches /to/ the target block
Check loops are in simplified form (have preheader etc) and LCSSA form.
Don't try to propagate old or thread-global flags to nulls or constants
Note subvalues of Deallocated properly
Don't print ignored blocks in brief mode, similar to dead blocks