Berkeley changes to dump since 4.3bsd

dump.h:
    added dev_bsize variable

dumptape:
    made dev_bsize a variable
    adjusted spcl.c_count in case of new-tape record to say how many
	blocks of file are carried over from previous tape
    sets DR_NEWHEADER flag for TS_TAPE record

dumpmain:
    sets spcl.c_filesys, spcl.c_dev, spcl.c_label (but not spcl.c_host)
    calculates dev_bsize from filesystem params

dumptraverse:
    made dev_bsize a variable

dumprmt:
    picked at lint

dumpitime:
dumpoptr:
unctime:
    no change
