base: Local signal submit
lxip: Port of the Linux TCP/IP stack
netperf: Add separate run scripts for lwip/lxip

Also removed target 'app/netperf' and added 'app/netperf/lwip' and
'app/netperf/lxip'.
libports: libc_block plugin

This plugin provides support for using a Block_session connection by
opening "/dev/blkdev".

Fixes #965.
libports: add sys/disk.h symlink

Fixes #965.