CppTools: Compile fix

Amends ef8de6a384516c.

Change-Id: I50dc5b63867888ed258d6dedf643c3cc33b1014c
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/plugins/cpptools/headerpathfilter.cpp

@@ -25,6 +25,10 @@
 
 #include "headerpathfilter.h"
 
+#ifndef UNIT_TESTS
+#include <coreplugin/icore.h>
+#endif
+
 #include <QRegularExpression>
 
 namespace CppTools {