Look at the preceding CFGBlock for the expression to load from in ExprEngine::VisitGuardedExpr
instead of walking to the preceding PostStmt node.  There are cases where the last evaluated
expression does not appear in the ExplodedGraph.

Fixes PR 13466.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160819 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed