libc_fs: Fix seek report for ro (non-append) files
libports/SDL: Add ttf, image, mixer, loadso
libports: Add GNU FriBidi
timer: bugfix and test trigger_periodic (run/timer)

Fix #699
usb: enable 64bit support for x86

Fix #436
base: hand over Pd_connection label to Platform_pd

fix: #656
terminal_mux.run: Don't use uart_drv on Fiasco.OC
nic_bridge: drop 'gratuitous ARP' messages

'Gratuitous ARP' broadcast messages are used to announce newly created
IP<->MAC address mappings to other hosts. nic_bridge-internal hosts
would expect a nic_bridge-internal MAC address in this message, whereas
external hosts would expect the NIC's MAC address in this message.
The simplest solution to this problem is to just drop those messages,
since they are not really necessary.

Fixes #709.