CMake build: Make errors of execute_process fail the build

Instead of silenty failing and resulting in broken builds/packages.

The property is only available since CMake 3.19, so limit the feature to
that.

Change-Id: I82b06e78540e81a809f7fdfe130648becfc9672e
Reviewed-by: Cristian Adam <cristian.adam@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

cmake/Utils.cmake

@@ -47,6 +47,7 @@ function(setup_dependencies_component)
           \"\${_ide_app_target}\"
           \"${_qmake_binary}\"
           COMMAND_ECHO STDOUT
+          \${QTC_COMMAND_ERROR_IS_FATAL}
           )
       "
       COMPONENT Dependencies