use proper values of apcu_cache_info() in apc.php

apcu_cache_info() returns these values:
```
Array
(
    [nslots] => 4099
    [ttl] => 0
    [nhits] => 0
    [nmisses] => 0
    [ninserts] => 0
    [nentries] => 0
    [nexpunges] => 0
    [stime] => 1406250445
    [mem_size] => 0
    [file_upload_progress] => 1
    [memory_type] => mmap
    [cache_list] => Array
        (
        )

    [deleted_list] => Array
        (
        )

    [slot_distribution] => Array
        (
        )

)
```
apc.php was using num_hits, num_misses, num_entries, num_expunges, start_time instead.