[analyzer] Weaken assertion to account for pointer-to-integer casts.

PR16690

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187132 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer] Add regression test for the crash in PR16664.

This goes with r186925, which reverted Pavel's commit in r186498.

Also, add a correctness test for the future.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187133 91177308-0d34-0410-b5e6-96231b3b80d8