illumos gate

Building with gcc 7 did reveal few issues:

    etm.c: In function 'etm_async_event_handler':
    etm.c:3199:27: error: comparison between pointer and zero character constant [-W
    error=pointer-compare]
          if (iosvc->ldom_name != '\0')
                               ^~
    etm.c:3199:10: note: did you mean to dereference the pointer?
          if (iosvc->ldom_name != '\0')
              ^
    cc1: all warnings being treated as errors
    *** Error code 1
    dmake: Warning: Command failed for target `etm.o'
    Current working directory /code/illumos-gate/usr/src/cmd/fm/modules/sun4v/etm

    cmd_Lxcacheerr.c: In function 'gen_data_for_ecc':
    cmd_Lxcacheerr.c:480:11: error: variable 'tag_ecc' set but not used [-Werror=unu
    sed-but-set-variable]
      uint16_t tag_ecc[PN_CACHE_NWAYS];
               ^~~~~~~
    cc1: all warnings being treated as errors

Testing done: build/install/boot.