Merge git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

Merge git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

* git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  asm-generic: add sys_recvmmsg to unistd.h
  asm-generic: add sys_accept4 to unistd.h
  asm-generic/gpio.h: add some forward decls of the device struct
  asm-generic: Fix typo in asm-generic/unistd.h.
  lib/checksum: fix one more thinko
  lib/checksum.c: make do_csum optional
  lib/checksum.c: use 32-bit arithmetic consistently