winrtrunner: Fix includepath

This was breaking for prefixed builds.

Change-Id: Ida0938b9d723bff81bcdc05b83d0da00bb59dc35
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>

src/winrtrunner/winrtrunner.pro

@@ -25,7 +25,7 @@ win32-msvc2012|win32-msvc2013 {
     HEADERS += \
         qzip/qzipreader_p.h \
         qzip/qzipwriter_p.h
-    INCLUDEPATH += qzip $$[QT_INSTALL_HEADERS]/QtZlib
+    INCLUDEPATH += qzip $$[QT_INSTALL_HEADERS/get]/QtZlib
 }
 
 load(qt_tool)