smallstring: Avoid size_t to (u)int warning

Change-Id: If206f0e3a90694b4e0d50e2d4569e0d6a34cf8ce
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/libs/utils/smallstringio.h

@@ -155,7 +155,7 @@ namespace std {
 template<> struct hash<Utils::SmallString>
 {
     using argument_type = Utils::SmallString;
-    using result_type = uint;
+    using result_type = std::size_t;
     result_type operator()(const argument_type& string) const
     {
         return qHashBits(string.data(), string.size());