Run the qttools cmake module tests only if QtWidgets is available.

Change-Id: I26847e3347cf24664ca52488ddf521c923e37912
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>

tests/auto/cmake/cmake.pro

@@ -2,6 +2,8 @@
 # Cause make to do nothing.
 TEMPLATE = subdirs
 
-qtHaveModule(widgets): CMAKE_QT_MODULES_UNDER_TEST = designer help uitools
+qtHaveModule(widgets) {
+    CMAKE_QT_MODULES_UNDER_TEST = designer help uitools
 
-CONFIG += ctest_testcase
+    CONFIG += ctest_testcase
+}