- fixed some issues with the bodyque and moved this variable into FLevelLocals

* it was never saved in savegames, leaving the state of dead bodies undefined
* it shouldn't be subjected to pointer substitution because all it contains is old dead bodies, not live ones.

src/g_level.cpp

@@ -1956,6 +1956,24 @@ void FLevelLocals::Tick ()
 //
 //==========================================================================
 
+void FLevelLocals::Mark()
+{
+	for (auto &s : sectorPortals)
+	{
+		GC::Mark(s.mSkybox);
+	}
+	// Mark dead bodies.
+	for (auto &p : bodyque)
+	{
+		GC::Mark(p);
+	}
+}
+
+//==========================================================================
+//
+//
+//==========================================================================
+
 void FLevelLocals::AddScroller (int secnum)
 {
 	if (secnum < 0)