php 查看扩展模块的信息或配置

比如，要查看memcache的信息
php --re  memcache   

查看memcache的配置选项
php --ri   memcache
结果如下：
memcache

memcache support => enabled
Active persistent connections => 0
Version => 2.2.7
Revision => $Revision: 327750 $

Directive => Local Value => Master Value
memcache.allow_failover => 0 => 0
memcache.max_failover_attempts => 20 => 20
memcache.default_port => 11211 => 11211
memcache.chunk_size => 8192 => 8192
memcache.hash_strategy => standard => standard
memcache.hash_function => crc32 => crc32
memcache.default_timeout_ms => 1000 => 1000