perl-gdgraph: fix configure

see http://autobuild.buildroot.org/results/3e1/3e1698b0523dfa46f5b3ee03a22af820f7342c39/build-end.log

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Try-Tiny: new package
Plack: all packages
moo: all packages
dancer2: all packages

TT: PERL_TEMPLATE_TOOLKIT_CONF_OPT = "TT_XS_ENABLE=n"
network interface eth0
defconfig
demo

set BR2_ROOTFS_OVERLAY with $(BR2_EXTERNAL)/overlay/
dancer2 skeleton

$ dancer2 gen -a MyWeb::App
Dancer2 as service
BR demo
add DateTime
add LWP-Protocol-https
add Chart-Plot-Tagged
add ntp in defconfig
update plot
user guest