proxmox: use L4 info for ECMP hashing

This should make VXLAN-encapsulated traffic multipath.

roles/proxmox/files/sysctl.conf

@@ -0,0 +1,3 @@
+# L4 (5-tuple) hashing for ECMP.
+net.ipv4.fib_multipath_hash_policy = 1
+net.ipv6.fib_multipath_hash_policy = 1

roles/proxmox/tasks/main.yml

@@ -28,6 +28,11 @@
     mode: 0644
   notify: reboot
 
+- name: Set up sysctls
+  copy:
+    dest: /etc/sysctl.d/local.conf
+    src: sysctl.conf
+
 - name: Set up interfaces
   template:
     dest: /etc/network/interfaces.d/real.intf