MFC r268123: MFV r268119:4914 zfs on-disk bookmark structure should be named *_phys_t
MFC r260150: MFV r259170:4370 avoid transmitting holes during zfs send4371 DMU code clean upillumos/illumos-gate@43466aae47bfcd2ad9bf501faec8e75c08095e4fNOTE: Make sure the boot code is updated if a zpool upgrade isdone on boot zpool.