[analyzer] Cache the bindings accessible through a LazyCompoundVal.

This means we don't have to recompute them all later for every
removeDeadSymbols check.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175233 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed