Pull Kbuild UAPI updates from Masahiro Yamada:
 "Improvement of headers_install by Nicolas Dichtel.

  It has been long since the introduction of uapi directories, but the
  de-coupling of exported headers has not been completed. Headers listed
  in header-y are exported whether they exist in uapi directories or
  not. His work fixes this inconsistency.

  All (and only) headers under uapi directories are now exported. The
  asm-generic wrappers are still exceptions, but this is a big step
  forward"

* tag 'kbuild-uapi-v4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  arch/include: remove empty Kbuild files
  uapi: export all arch specifics directories
  uapi: export all headers under uapi directories
  smc_diag.h: fix include from userland
  btrfs_tree.h: fix include from userland
  uapi: includes linux/types.h before exporting files
  Makefile.headersinst: remove destination-y option
  Makefile.headersinst: cleanup input files
  x86: stop exporting msr-index.h to userland
  nios2: put setup.h in uapi
  h8300: put bitsperlong.h in uapi