This is necessary in order not to make is_from_self be confused when receiving
any frame. Actually, MAC address should be get by the board and not fixed
inside the code.

The WRMODE option in Makefile acts as the -g option (run as slave only):
WRMODE=master -> auto detect, becomes master if no announce is received
WRMODE=slave  -> never go to master mode, listens for announce and becomes slave

See commit 9d37ccb1651edc3ea9dac25ebc3092420d84fdf5 in ptp-proposal

This is a major patch, because header files are renamed, and
the header directory with them. Still, no functional change is there.

Corrected the computation itself (do not move pointers, but the .start field!).
Define posix_timer_adjust_all and its alias pp_timer_adjust_all

Actually, the best way for implementing timers is to use MONOTONIC_RAW which
avoids the need of such an adjust function

PP_DEFAULT_NO_ADJUST must be set to 0, otherwise the slave would not adjust
the time. It can be set to 1 with -t parameter in cmd line: this can be useful
for debug purpose, but must not be the default.

The correct one is in rt_opts struct. Removed the oldest one, which was still
used (but not set to its default) and lead to a division by zero