Thanks everyone for all the comments and help. After removing an install of /opt/libpcap-0.9.8 since I had libpcap-0.9.4-12.el5 also installed; and re-running ./configure, make ran without errors. So did make install. Looks like my box is up and running.
Thank you!
Martin
PS. Looks like Bro INSTALL doc file might need updating to indicate that corresponding -devel- packages also need to be installed.