Network:  Add logic to get a default network device (for the case where are multiple devices).  For INADDR_ANY

apps/examples/bridge:  Lots of fixes.  I think it is working although I have still have host firewall issues in testing

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@haltian.com>

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>

Move IP header flags from tcp.h to ip.h and rename IP_FLAGS vs TCPFLAGS.  The problem fixed here is that there IP flags were not available when TCP was disabled.  The IP flags are used in ICMP and IGFMP

Due to limitations in port unique-ness, have to use unique port numbers in apps/examples/bridge for now