The information above is not sufficient to diagnose what the problem is. My guess is that the builtin libpcre failed to configure or build. I recommend installing it in the system instead of enabling the builtin version. You can try installing the list of packages for CentOS 7 from this file to get all dependencies ROOT needs. To enable support for all of it, just configure with cmake -Dall=ON $srcdir.
Please try reconfiguring cmake to use the system library now with cmake . -Dbuiltin_pcre=OFF. I think you are not missing anything, only pcre-devel is sufficient as far as I know from the list above.