Implement IntervalMap destructor.

Key and value objects may not be destructed instantly when they are erased from
the container, but they will be destructed eventually by the IntervalMap
destructor.

llvm-svn: 119873

llvm/include/llvm/ADT/IntervalMap.h

@@ -848,6 +848,11 @@ public:
     new(&rootLeaf()) RootLeaf();
   }
 
+  ~IntervalMap() {
+    clear();
+    rootLeaf().~RootLeaf();
+  }
+
   /// empty -  Return true when no intervals are mapped.
   bool empty() const {
     return rootSize == 0;