It is possible, under specific circumstances involving ptrtoint ConstantExpr's, for...

It is possible, under specific circumstances involving ptrtoint ConstantExpr's, for LVI to end up trying to merge
a Constant into a ConstantRange.  Handle this conservatively for now, rather than asserting.  The testcase is
more complex that I would like, but the manifestation of the problem is sensitive to iteration orders and the state of the
LVI cache, and I have not been able to reproduce it with manually constructed or simplified cases.

Fixes PR8162.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114103 91177308-0d34-0410-b5e6-96231b3b80d8