Fix configuring error when QtQml is not around
In ECM the included module fails if a QML specific cmake function is not around. Consequently, we should only include it when we have the flag to build with QML set.
if ("${QT_MAJOR_VERSION}" STREQUAL "6")
include(${CMAKE_CURRENT_LIST_DIR}/ECMQmlModule6.cmake)
if (NOT COMMAND ecm_add_qml_module)
message(FATAL_ERROR "Failed setting up ECMQmlModule")
endif()