seoul: refresh console only if required

Speeds up kernelbuild by over 35% !!!
seoul: support headless mode

+ run kernelbuild in headless mode, output dumped via serial output
run: support target serial for base-nova

Issue #683
noux: start time measuring with first noux output

Don't account the boottime to the actual compile time - since it varies quite
a lot if somebody else utilize the network with lwip tests for example ;-).
terminal: refresh only if output changed
noux: add verbose config parameter

Explicitly enable verbose output if required.
ldso: be quiet by default
signal test: let sender yield CPU when idle

ref #574
hw: fix in signal-ack handling in kernel

ref #574
hw: don't unmask timer IRQ on any kernel pass

ref #855
hw: touch kernel scheduler and timer less often

fix #857
fix #855
foc: print line numbers in decimal on assert
base: fix thread_cap initialization

Fixes #842
base: fix pausing tracing subjects

Fixes #858.
dde_linux: remove superfluous 'msleep()' calls

Fixes #860.
acpi: skip parameters of DefName

Fixes #415
libports: remove right files when cleaning libc

Only the directories and files which were created in the first place
by the libc port should be removed. Thereby ignore the exit code of
the find command to prevent GNUmake from stopping its execution.

Fixes #841.
usb_drv: change Driver_context to Signal_dispatcher

Fixes #861
ffat: require prepare_ffat if ffat not prepared

fix #534
mmio: interpret read-verbosity switch

fix #825