illumos gate

Build errors with gcc 12:

    ../common/shp.c: In function 'find_physical_slot_names':
    ../common/shp.c:1166:35: error: the comparison will always evaluate as 'true' for the address of 'slotnames' will never be NULL [-Werror=address]
     1166 |         if (slotarg->slotnames[0] != NULL)
          |                                   ^~
    ../common/shp.c:274:17: note: 'slotnames' declared here
      274 |         char    slotnames[MAXDEVS][MAXNAMELEN];
          |                 ^~~~~~~~~
    cc1: all warnings being treated as errors

    ../common/cfga.c: In function 'find_physical_slot_names':
    ../common/cfga.c:1296:35: error: the comparison will always evaluate as 'true' for the address of 'slotnames' will never be NULL [-Werror=address]
     1296 |         if (slotarg->slotnames[0] != NULL)
          |                                   ^~
    ../common/cfga.c:261:17: note: 'slotnames' declared here
      261 |         char    slotnames[MAXDEVS][MAXNAMELEN];
          |                 ^~~~~~~~~
    cc1: all warnings being treated as errors

Indeed, the arrays are allocated and therefore never NULL. Which always leads us to the question if the check is needed or if the condition statement is wrong.

Testing done: build, install, boot, cfgadm command appears to work as expected.
wsdiff does show differences in constants, but also the added call to memset() did cause additional noise.