Return UnknownVal in RegionStoreManager::getSizeInElements() for unsupported regions.  This silences a warning when compiling Release-Asserts builds.

llvm-svn: 61818
diff --git a/clang/lib/Analysis/RegionStore.cpp b/clang/lib/Analysis/RegionStore.cpp
index 602d6bd..4e0215b 100644
--- a/clang/lib/Analysis/RegionStore.cpp
+++ b/clang/lib/Analysis/RegionStore.cpp
@@ -431,6 +431,7 @@
   }
 
   assert(0 && "Other regions are not supported yet.");
+  return UnknownVal();
 }
 
 /// ArrayToPointer - Emulates the "decay" of an array to a pointer