ctest: Make cmake test pass if it has been run before

We have to check if the directory exists before calling mkdir or the test
will fail on every run but the first one.

Change-Id: I36f10cfc18b3cb99990dc96190349ee00a0c1c4e
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

mkspecs/features/ctest_testcase_common.prf

@@ -65,7 +65,8 @@ for (MODULE_UNDER_TEST, CMAKE_QT_MODULES_UNDER_TEST) {
 CMAKE_MODULES_UNDER_TEST = $$join(CMAKE_MODULES_UNDER_TEST, ;)
 
 check.commands = \
-    $(MKDIR) $$BUILD_DIR && $$QMAKE_CD $$BUILD_DIR && \
+    $$sprintf($$QMAKE_MKDIR_CMD, $$BUILD_DIR) $$escape_expand(\\n\\t) \
+    $$QMAKE_CD $$BUILD_DIR && \
     cmake $$CMAKE_TEST_LOCATION $$CMAKE_GENERATOR \
         -DCMAKE_C_COMPILER=$$QMAKE_CC \
         -DCMAKE_CXX_COMPILER=$$QMAKE_CXX \