Implement @(fini) (opposite of @(init))

src/entity.cpp

@@ -75,6 +75,7 @@ enum EntityFlag : u64 {
 	EntityFlag_Test          = 1ull<<30,
 	EntityFlag_Init          = 1ull<<31,
 	EntityFlag_Subtype       = 1ull<<32,
+	EntityFlag_Fini          = 1ull<<33,
 	
 	EntityFlag_CustomLinkName = 1ull<<40,
 	EntityFlag_CustomLinkage_Internal = 1ull<<41,