use latest version of libhermit

- fix initialization of virtio network driver

switch to libhermit-rs 0.6.3

- switch to libhermit-rs 0.6.3
- add the option to disable the FUSE support

Fix symbol typo

Fix symbol typo: sys_processor_count -> sys_get_processor_count

download the latest kernel 0.6.1

add BSD socket interface

- declare Rust ABI as deprecated
- use always a C interface to the kernel
- add read_entropy syscall (#395)

move smoltcp to libhermit.rs

remove deadlock within the network stack

To avoid deadlocks, spinlocks and the device checks are revised. In principle, the network thread doesn't block, if another thread is already checking the device.

In addition, the send and receive operations are optimized to stay longer in polling mode and assign the network handler to the core, where the network thread is running. This should reduce the number of wakeup interrupts.

add try_lock support for spinlock

Without try_lock support, the mutex isn't able to avoid busy waiting.

switch to libhermit 0.4.2 to remove some issues with the RTL8139 driver

revise network configuration by DHCP

Add block_current_task_with_timeout syscall

switch to libhermit v0.4.1

revise network interface

revise mutex interface