Remove extra loop counter data dependancy in `map_haystacks()` error rollback path.

Fortune for naka's current commit: Small curse − 小凶

src/main.c

@@ -59,8 +59,8 @@ static int map_haystacks(const char* const * h, map_t maps[pOUT])
 			// Prep reset maps to before `c` for unwind
 			maps-=1;
 			ERROR("Failed to map file `%s', rolling back %lu maps. (erp: %p, prev: %p)", path, d, c, maps);
-			for(usize i=0;i<d;i++)
+			while( d --> 0 )
-				if(!map_handle_err(map_free(* (--maps)))) WARN("Failed to free map at %p (in %lu unwind)", maps, i);
+				if(!map_handle_err(map_free(* (--maps)))) WARN("Failed to free map at %p (in %lu unwind)", maps, d);
 			return 0;
 		}
 		d+=1;