Clang: Fix completion after '{'

Follow-up fix for 8d0391a4f9.

Do not complete after '{' coming not after an identifier.
Take constructor completions only for '{' and function
completions only for '('. Filter constructor completions by
class/struct type.

Task-number: QTCREATORBUG-21004
Change-Id: I7ae2d6bee23cf907648c42b93eb12742942833f6
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/libs/sqlite/utf8string.h

@@ -131,6 +131,16 @@ public:
         return byteArray.indexOf(text);
     }
 
+    int lastIndexOf(const Utf8String &text) const
+    {
+        return byteArray.lastIndexOf(text.byteArray);
+    }
+
+    int lastIndexOf(const char *text) const
+    {
+        return byteArray.lastIndexOf(text);
+    }
+
     int indexOf(char character) const
     {
         return byteArray.indexOf(character);