php -m

gistfile1.txt

Drupal 7
Fatal error: Undefined class constant 'MYSQL_ATTR_USE_BUFFERED_QUERY' in includes/database/mysql/database.inc on line 46

$ php -m
PHP Warning:  PHP Startup: Unable to load dynamic library '/usr/lib64/php/modules/mysql.so' - libmysqlclient.so.15: cannot open shared object file: No such file or directory in Unknown on line 0
PHP Warning:  PHP Startup: Unable to load dynamic library '/usr/lib64/php/modules/mysqli.so' - libmysqlclient.so.15: cannot open shared object file: No such file or directory in Unknown on line 0
PHP Warning:  PHP Startup: Unable to load dynamic library '/usr/lib64/php/modules/pdo_mysql.so' - libmysqlclient.so.15: cannot open shared object file: No such file or directory in Unknown on line 0
[PHP Modules]
apc
bz2
calendar
Core
ctype
curl
date
dom
ereg
exif
fileinfo
filter
ftp
gd
gettext
gmp
hash
iconv
json
ldap
libxml
mbstring
mcrypt
memcache
newrelic
openssl
pcntl
pcre
PDO
pdo_sqlite
Phar
readline
Reflection
session
shmop
SimpleXML
sockets
SPL
sqlite3
standard
tokenizer
uploadprogress
wddx
xml
xmlreader
xmlwriter
xsl
zip
zlib

[Zend Modules]

$ locate libmysqlclient.so
/usr/lib64/mysql/libmysqlclient.so.15
/usr/lib64/mysql/libmysqlclient.so.15.0.0
/usr/lib64/mysql/libmysqlclient.so.18
/usr/lib64/mysql/libmysqlclient.so.18.0.0
/usr/lib64/mysql5/mysql/libmysqlclient.so.15
/usr/lib64/mysql5/mysql/libmysqlclient.so.15.0.0

$ ls -l /usr/lib64/php/modules/
total 6944
-rw-r--r-- 1 root root  688390 Oct  1 11:29 apc.so
-rwxr-xr-x 1 root root   65056 Dec 18 19:44 curl.so
-rwxr-xr-x 1 root root  167016 Dec 18 19:44 dom.so
-rwxr-xr-x 1 root root 2369568 Dec 18 19:44 fileinfo.so
-rwxr-xr-x 1 root root  332032 Dec 18 19:44 gd.so
-rwxr-xr-x 1 root root   32984 Dec 18 19:44 json.so
-rwxr-xr-x 1 root root   52184 Dec 18 19:44 ldap.so
-rwxr-xr-x 1 root root 2146576 Dec 18 19:44 mbstring.so
-rwxr-xr-x 1 root root   46760 Aug  3  2011 mcrypt.so
-rwxr-xr-x 1 root root   95504 Apr  8  2013 memcache.so
-rwxr-xr-x 1 root root  132720 Dec 18 19:44 mysqli.so
-rwxr-xr-x 1 root root   54328 Dec 18 19:44 mysql.so
lrwxrwxrwx 1 root root      53 Sep 19 15:36 newrelic.so -> /usr/lib/newrelic-php5/agent/x64/newrelic-20090626.so
-rwxr-xr-x 1 root root   32744 Dec 18 19:44 pdo_mysql.so
-rwxr-xr-x 1 root root   98504 Dec 18 19:44 pdo.so
-rwxr-xr-x 1 root root   25160 Dec 18 19:44 pdo_sqlite.so
-rwxr-xr-x 1 root root  258336 Dec 18 19:44 phar.so
-rwxr-xr-x 1 root root   15416 Jan 18  2012 phpcups.so
-rwxr-xr-x 1 root root   51004 Oct  4  2011 uploadprogress.so
-rwxr-xr-x 1 root root   32760 Dec 18 19:44 wddx.so
-rwxr-xr-x 1 root root   29208 Dec 18 19:44 xmlreader.so
-rwxr-xr-x 1 root root   45528 Dec 18 19:44 xmlwriter.so
-rwxr-xr-x 1 root root   33976 Dec 18 19:44 xsl.so
-rwxr-xr-x 1 root root   90496 Dec 18 19:44 zip.so

$ namei -m /usr/lib64/php/modules/pdo_mysql.so
f: /usr/lib64/php/modules/pdo_mysql.so
 drwxr-xr-x /
 drwxr-xr-x usr
 drwxr-xr-x lib64
 drwxr-xr-x php
 drwxr-xr-x modules
 -rwxr-xr-x pdo_mysql.so