[DAGCombine] Revert of recommit of "binop-with-const hoisting" patches

[DAGCombine] Revert of recommit of "binop-with-const hoisting" patches

I was looking into an endless combine loop the uncommitted follow-up patch
was causing, and it appears even these patches can exibit such an
endless loop. The root cause is that we try to hoist one binop (add/sub) with
constant operand, and if we get two such binops both of which are
eligible for this hoisting, we get stuck.

Some cases may highlight missing constant-folds.

Reverts r361871,r361872,r361873,r361874.

llvm-svn: 362109