wget https://github.com/websupport-sk/pecl-memcache/archive/NON_BLOCKING_IO_php7.zip
unzip NON_BLOCKING_IO_php7.zip
cd pecl-memcache-NON_BLOCKING_IO_php7/
/usr/local/Cellar/php@7.1/7.1.20/bin/phpize 
./configure --enable-memcache --with-php-config=/usr/local/Cellar/php@7.1/7.1.20/bin/php-config
make 
make install
然后把extension = "/usr/local/Cellar/php@7.1/7.1.20/pecl/20160303/memcache.so"  
添加到/usr/local/etc/php/7.0/php.ini 结尾就行
最后重启php-fpm