php部分自带扩展，在源码包里已有，不用再找第三方去下载：如 php_mysql, php_dblib等。
[root@test ext]# ls /usr/local/src/php-5.5.13/ext
bcmath fileinfo mbstring pdo_firebird shmop tokenizer
bz2 filter mcrypt pdo_mysql simplexml wddx
calendar ftp mssql pdo_oci skeleton xml
com_dotnet gd mysql pdo_odbc snmp xmlreader
ctype gettext mysqli pdo_pgsql soap xmlrpc
curl gmp mysqlnd pdo_sqlite sockets xmlwriter
date hash oci8 pgsql spl xsl
dba iconv odbc phar sqlite3 zip
dom imap opcache posix standard zlib
enchant interbase openssl pspell sybase_ct
ereg intl pcntl readline sysvmsg
exif json pcre recode sysvsem
ext_skel ldap pdo reflection sysvshm
ext_skel_win32.php libxml pdo_dblib session tidy
