Fixed issue with actors occasionally unaffected by dynamic lights

https://mantis.zdoom.org/view.php?id=536

src/g_shared/a_dynlightdata.cpp

@@ -170,6 +170,7 @@ FLightDefaults::FLightDefaults(FName name, ELightType type)
 	m_additive = false;
 	m_halo = false;
 	m_dontlightself = false;
+	m_dontlightactors = false;
 	m_attenuate = -1;
 }