ProjectExplorer: Mark Kit c'ctor and c'assignment as deleted

... instead of not implementing it.

Change-Id: I5f004ae5e6152bf935faa4cbc5a3b29b68e85808
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/projectexplorer/kit.h

@@ -146,9 +146,8 @@ private:
     static void copyKitCommon(Kit *target, const Kit *source);
     void setSdkProvided(bool sdkProvided);
 
-    // Unimplemented.
-    Kit(const Kit &other);
-    void operator=(const Kit &other);
+    Kit(const Kit &other) = delete;
+    void operator=(const Kit &other) = delete;
 
     void kitUpdated();