This library is from pam-devel package as you can see here, so install the required package, you may need to install i686 version of the package.
[root@ansible-host lib64]# find / -iname libpam.so 2>/dev/null /usr/lib64/libpam.so [root@ansible-host lib64]# rpm -qf /usr/lib64/libpam.so pam-devel-1.1.1-22.el6.x86_64