Make some qHash and comparison operators overloads hidden friends

Restricts lookup scope more to necessary bits.

Change-Id: Ia42c95aaa70534843b7f6a90bfc56d2a1202c612
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/qtcprocess.h

@@ -218,6 +218,4 @@ private:
 
 using ExitCodeInterpreter = std::function<QtcProcess::Result(int /*exitCode*/)>;
 
-QTCREATOR_UTILS_EXPORT QDebug operator<<(QDebug str, const QtcProcess &);
-
 } // namespace Utils