Clang: clean up unit handling.

- Use a QSharedPointer instead of an explicitly shared pointer.
- Remove the LiveUnitManager.

Change-Id: I05bf32c1f77c17f42ee1da39f1353cff580fa6eb
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>

src/plugins/clangcodemodel/clangindexer.h

@@ -72,7 +72,7 @@ public:
 
     void match(ClangSymbolSearcher *searcher) const;
 
-    void indexNow(const Unit &unit);
+    void indexNow(Unit::Ptr unit);
 
 public slots:
     void onAboutToLoadSession(const QString &sessionName);