Explicitly include qloggingcategory.h

Do not rely on QLoggingCategory being implicitly declared through
other headers.

Pick-to: 6.2
Change-Id: Ib6cda43f281d31a7127dd591be2540fb00a0a699
Reviewed-by: Maximilian Goldstein <max.goldstein@qt.io>

tools/qmllint/main.cpp

@@ -48,6 +48,7 @@
 #include <QtCore/qjsonobject.h>
 #include <QtCore/qjsonarray.h>
 #include <QtCore/qjsondocument.h>
+#include <QtCore/qloggingcategory.h>
 #include <QtCore/qscopeguard.h>
 
 #if QT_CONFIG(commandlineparser)

tools/qmltc/qmltccompiler.cpp

@@ -29,6 +29,7 @@
 #include "qmltccompiler.h"
 #include "qmltcoutputir.h"
 #include "qmltccodewriter.h"
+#include <QtCore/qloggingcategory.h>
 
 QT_BEGIN_NAMESPACE