remove (a+b)*c => a*c + b*c reassoc rule for now

This rule produces more nodes than before and is therefore very
dangerous. The original argument that localopt rules will revert this in
non-profitable cases is not good enough as in combination with CSE, etc.
not everything will get reverted.

In the future someone could write an analysis that can detect cases
where the rule will have a positive effect and reenable it for these
cases.
remove old buggy escape_analysis

You can always revive it from older revision, although I would strongly
suffest to start from scratch.
constbits: cleanup, use C99
dca: cleanup
occult_const: cleanup
amd64: Fixed unsigned Div. Improved IDiv but not in all cases