No need for gawk

Awk isn't used in libvirt anymore and virt-pki-validate can cope
with mawk.

Closes: #703380

debian/control

@@ -65,7 +65,6 @@ Recommends: netcat-openbsd,
  iptables (>= 1.4.10),
  qemu-kvm | qemu (>= 0.9.1),
  libxml2-utils,
- gawk,
  ebtables,
  dmidecode,
  iproute,