Fix test

The memory occupied by “dummy” should be large enough for one of the
entries inserted by the loop to fit into it. This allows the last
inserted record of the loop (which triggers expunge) to replace this
entry, which prevents a real_expunge of the whole cache.

Author: madmajestro

tests/apc_020.phpt

@@ -17,7 +17,7 @@ apc.shm_size=1M
 apcu_store("no_ttl_unaccessed", 12);
 apcu_store("no_ttl_accessed", 24);
 apcu_store("ttl", 42, 3);
-apcu_store("dummy", "xxx");
+apcu_store("dummy", str_repeat('x', 1000));
 
 apcu_inc_request_time(1);
 apcu_fetch("no_ttl_accessed");