[analyzer] Update RegionStoreManager::getBinding to handle BlockDataRegions

[analyzer] Update RegionStoreManager::getBinding to handle BlockDataRegions

Update RegionStoreManager::getBinding() to return UnknownVal when trying to get
the binding for a BlockDataRegion. Previously, getBinding() would try to cast the
BlockDataRegion to a TypedValueRegion and crash. This happened when a block
was passed as a parameter to an inlined function for which
StackHintGeneratorForSymbol::getMessage() tried to generate a stack hint message.

rdar://problem/21291971

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@252185 91177308-0d34-0410-b5e6-96231b3b80d8