Merge pull request #8857 from ZetaR60/RIOT_atmega_time_dot_h

cpu/atmega_common/Makefile.include

cpu/atmega_common/include/sys/stat.h

cpu/atmega_common/include/sys/types.h

cpu/atmega_common/include/vendor/errno.h

cpu/atmega_common/include/vendor/inttypes.h

cpu/atmega_common/include/vendor/time.h

cpu/atmega_common/include/vendor/unistd.h

sys/include/tm.h

sys/timex/tm.c

tests/pkg_minmea/Makefile

tests/struct_tm_utility/main.c