If you’re trying to compile PHP with MySQL on CentOS x86_64 you may get this error:
checking for mysql_close in -lmysqlclient... no
checking for mysql_error in -lmysqlclient... no
configure: error: mysql configure failed. Please check config.log for more information.
You can fix it by adding --with-libdir=lib64
to your config-options
file or whatever compilation script you are using.