Add missing call to Optional<...>.getValue() that was pointed out by Chandler.

llvm-svn: 94678
diff --git a/clang/lib/Checker/RegionStore.cpp b/clang/lib/Checker/RegionStore.cpp
index 7fb9c0f..376921f 100644
--- a/clang/lib/Checker/RegionStore.cpp
+++ b/clang/lib/Checker/RegionStore.cpp
@@ -1596,7 +1596,7 @@
     
     // We assume that string constants are bound to
     // constant arrays.
-    uint64_t size = Size;
+    uint64_t size = Size.getValue();
     
     for (uint64_t i = 0; i < size; ++i, ++j) {
       if (j >= len)