[LVI] Apply transfer rule for overdefine inputs for binary operators

As pointed out by John Regehr over in http://reviews.llvm.org/D19485, LVI was being incredibly stupid about applying its transfer rules.  Rather than gathering local facts from the expression itself, it was simply giving up entirely if one of the inputs was overdefined.  This greatly impacts the precision of the overall analysis and makes it far more fragile as well.

This patch builds on 267609 which did the same thing for unary casts.

llvm-svn: 267620