If your cPanel server has /tmp mounted with the noexec option you may run into the following error when trying to install the extention.
"checking whether the C compiler works... configure: error: cannot run C compiled programs."
You can remount /tmp with exec, run the pecl install and than remount /tmp again with no exec:
- mount -o,remount,rw,exec /var/tmp
- pecl install mongo
- mount -o,remount,rw,noexec /var/tmp
If you are not comfortable remounting /tmp. You can try the following instead which will create a symlink to another mount that doesn't have the noexec option.
- mkdir /root/tmp.pear
- mkdir /root/tmp.pear-build-root
- rm -rf /tmp/pear*
- ln -s /root/tmp.pear /tmp/pear
- ln -s /root/tmp.pear-build-root /tmp/pear-build-root
- pecl install mongo