Squashed commit of the following:
sched: Rename all use of system_t to clock_t.
syscall: Rename all use of system_t to clock_t.
net: Rename all use of system_t to clock_t.
libs: Rename all use of system_t to clock_t.
fs: Rename all use of system_t to clock_t.
drivers: Rename all use of system_t to clock_t.
arch: Rename all use of system_t to clock_t.
include: Remove definition of systime_t; rename all use of system_t to clock_t.
timeout. Immediate timeout is achieved by setting absolute timeout value to
past time, for example abstime={ .tv_sec=0, .tv_nsec=0 }. However absolute
time was converted to relative time using unsigned integer arithmetic and
resulted large ticks count by clock_abstime2ticks, instead of expected negative
ticks value.
Patch corrects clock_abstime2ticks to return negative ticks, if absolute time
is in the past.
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@haltian.com>