[analyzer] MoveChecker: Improve invalidation policies.

[analyzer] MoveChecker: Improve invalidation policies.

If a moved-from object is passed into a conservatively evaluated function
by pointer or by reference, we assume that the function may reset its state.

Make sure it doesn't apply to const pointers and const references. Add a test
that demonstrates that it does apply to rvalue references.

Additionally, make sure that the object is invalidated when its contents change
for reasons other than invalidation caused by evaluating a call conservatively.
In particular, when the object's fields are manipulated directly, we should
assume that some sort of reset may be happening.

Differential Revision: https://reviews.llvm.org/D55289

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@349190 91177308-0d34-0410-b5e6-96231b3b80d8