stage: only warn about deprecated when QI_WARN_DEPRECATED is ON
stage: only warn about deprecated when QI_WARN_DEPRECATED is ON

fix #4460

dmerejkowsky/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild