GRStateRef:

- Rename SetSVal to BindLoc
- Add BindDecl
- Add BindExpr

GRState:
- Environment now binds to Stmt* instead of Expr*.  This is needed for processing ObjCForCollectionStmt (essentially the declaration of the the 'element' variable can have an SVal attached to it).
- BindDecl no longer accepts Expr* for the initialization value; use SVal* instead.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59152 91177308-0d34-0410-b5e6-96231b3b80d8