Prevent multiple inclusions of logging.h

Also provide destructor of QLoggingCategory inline.

Change-Id: Ic12cd0347eddcbfaddbd93ea8e9b9baa3307973f
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>

src/libs/utils/logging.h

@@ -28,6 +28,7 @@
 ****************************************************************************/
 
 #ifndef LOGGING_H
+#define LOGGING_H
 
 #include <qglobal.h>
 
@@ -42,7 +43,7 @@ class QLoggingCategory
     Q_DISABLE_COPY(QLoggingCategory)
 public:
     explicit QLoggingCategory(const char *category) : name(category) {}
-    ~QLoggingCategory();
+    ~QLoggingCategory() {}
     static void setFilterRules(const QString &) {}
 
     bool isDebugEnabled() const { return false; }