run: lwip use is_qemu
run: support RUN_OPT for all platforms

Use RUN_OPT="--target ..." to select the backend test method.

Supported values so far:

qemu     - qemu + grub bootloader (default)
qemu+pxe - qemu + pulsar bootloader (PXE)
amt      - Intel AMT (reset+serial output) + pulsar bootloader

Related to issue #598
dde_ipxe: fix null pointer de-referencing
dde_ipxe: catch exception instead of dying silently
check wakeup situation in rx() after dequeuing

Issue #593
tool: add support to specify serial via RUN_OPT

If the target machine is connected locally one may specify
"serial" as target in the RUN_OPT variable to get the test output.
run: add nic driver performance test

A run script which sends raw ethernet packets from the host machine to the
target machine. Three tests are implemented:
- The network_stat instrumented driver of usb_drv and net_drv
  are used to get the raw receive performance of the network driver.
- A simple nic_session client is receiving from the un-instrumented network
  driver raw ethernet packets.
- A bridge is added between driver and simple nic_session client.
run: add lwip pingpong test using tcp
run: adjust lwip pingpong test for foc_arndale
run: adjust lwip pingpong test for x86
dde_ipxe: add support to forward a second mac

For the network_test_raw_bridge_client. Ethernet packets for the second mac
will also be accepted by the driver and forwarded to the network_bridge