Fix error 'call of overloaded ... is ambiguous'

With Qt 5.9, I got an error when calling compare(BlackMisc::Network::CEntityFlags::Entity,
BlackMisc::Network::CEntityFlags::Entity). The underlying integral type
of an enum is implementation defined and gcc seem to choose an unsigned
int in this case. This made the call ambiguous, since there was no unsigned
int overload yet of compare.

src/blackmisc/comparefunctions.cpp

@@ -26,6 +26,12 @@ namespace BlackMisc
             return a < b ? -10 : 10;
         }
 
+        int compare(uint a, uint b)
+        {
+            if (a == b) return 0;
+            return a < b ? -10 : 10;
+        }
+
         int compare(qint64 a, qint64 b)
         {
             if (a == b) return 0;