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.
Fix some typos
ram_fs: use server skeleton library

Related to #944.
base-linux: hybrid file-system server

The current implementation is missing support for symbolic links.

Fixes #944.
gpio_drv: Fix linking on PandaBoard

Issue #708
usb_drv: Use GPIO driver on PandaBoard

Also updated run scripts.

Issue #708
cpu_session: follow-up fix for scale_priority

This is a fixup for commit 5a42f40f04981581327639a75298e9e653ef39f5.

ref #961
base: Warn on undissolved signal contexts
Dissolve sig contexts in rm_fault and signal tests
hw: no default values for kernel-call args

ref #967
hw: make bootstrap save against multiple calls

In programs with dynamic linker, _main and thus also platform_main_bootstrap
are called twice. By now, platform_main_bootstrap tried to always access the
startup message in the UTCB of the main thread that gets overridden till the
second call.

fix #967