Update the configure script check for libpri to check for the newest function

that was just added.

Cresl1n, please keep this in mind when making these changes to libpri or libss7.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89615 65c4cc65-6c06-0410-ace0-fbb531ad65f3