Set qt_add_test WORKING_DIRECTORY to OUTPUT_DIRECTORY

If qt_add_test() is called with OUTPUT_DIRECTORY and no
WORKING_DIRECTORY is specified, default the WORKING_DIRECTORY to the
same value as OUTPUT_DIRECTORY._

Change-Id: If373fe590508ad58d4632e0598cd0d9dddb2ae16
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

cmake/QtBuild.cmake

@@ -2724,6 +2724,8 @@ function(qt_add_test name)
         else()
             if (arg_WORKING_DIRECTORY)
                 set(test_working_dir "${arg_WORKING_DIRECTORY}")
+            elseif(arg_OUTPUT_DIRECTORY)
+                set(test_working_dir "${arg_OUTPUT_DIRECTORY}")
             else()
                 set(test_working_dir "${CMAKE_CURRENT_BINARY_DIR}")
             endif()