Makefile: Disable static builds of flanneld
Makefile: Disable static builds of flanneld

It causes problems with the gce backend and I believe it's hitting
this bug https://sourceware.org/bugzilla/show_bug.cgi?id=19341

adiclepcea/flannel,adiclepcea/flannel,adiclepcea/flannel,coreos/flannel,coreos/flannel,coreos/flannel