Codechange: do not use MallocT for the pool

Needed to make the placement new operator use Tindex over size_t because of
ambiguity for the delete operator variant that also has the size.

src/saveload/subsidy_sl.cpp

@@ -48,7 +48,7 @@ struct SUBSChunkHandler : ChunkHandler {
 
 		int index;
 		while ((index = SlIterateArray()) != -1) {
-			Subsidy *s = new (index) Subsidy();
+			Subsidy *s = new (SubsidyID(index)) Subsidy();
 			SlObject(s, slt);
 		}
 	}