/usr/bin/gdlib-config is owned by package: gd-devel
Install that with yum, and it should work as to _that_ test.
I already did install that.
see:
rpm -qa | grep gd
gd-devel-2.0.28-5.4E gd-progs-2.0.28-5.4E gdbm-1.8.0-24 sysklogd-1.4.1-26_EL gd-2.0.28-5.4E php-gd-4.3.9-3.22.9