[InstCombine] allow icmp+binop folds before min/max bailout (PR43310)

This has the potential to uncover missed analysis/folds as shown in the
min/max code comment/test, but fewer restrictions on icmp folds should
be better in general to solve cases like:
https://bugs.llvm.org/show_bug.cgi?id=43310

llvm-svn: 372510