PHP 5.5.xの，mysqliオプションです．なかなか難航しています^^;
EXTENSION_DIR=/usr/lib/php/extensions \ CFLAGS="-O2 -march=i486 -mtune=i686" \ ./configure --prefix=/usr --localstatedir=/var \ --sysconfdir=/etc --mandir=/usr/man --infodir=/usr/info \ --enable-shared --with-config-file-scan-dir=/etc/php \ --with-config-file-path=/etc/httpd --with-apxs2=/usr/sbin/apxs \ --enable-mbstring --with-gettext --with-mysqli --with-mcrypt \ --with-ldap --with-zlib --with-gd --with-jpeg-dir=/usr/lib \ --with-png-dir=/usr/lib --with-mysql --build=i486-slackware-linux