hack, work around clang __attribute__((packed)) bugs in m30.h and m62.h
hack, rewrite scom struct for clang such that their alignment parser can cope
Revert "hack, rewrite scom struct for clang such that their alignment parser can cope"

This reverts commit fea6e21a22b2545ee32904f2616fba59859121b5.
hack, use 64b-wide bit fields to define scom_hdr_u, just to please clang
hygiene, remove unnecessary packed attribute from utehdr2_s struct def
hygiene, remove unnecessary packed attribute from struct zrng_s def
chore, import latest tzraw from dateutils (minus leap-second handling)
chore, follow-up adapt to new tzraw
Merge branch 'bld/clang'

* bld/clang:
  chore, follow-up adapt to new tzraw
  chore, import latest tzraw from dateutils (minus leap-second handling)
  hygiene, remove unnecessary packed attribute from struct zrng_s def
  hygiene, remove unnecessary packed attribute from utehdr2_s struct def
  hack, use 64b-wide bit fields to define scom_hdr_u, just to please clang
  Revert "hack, rewrite scom struct for clang such that their alignment parser can cope"
  hack, rewrite scom struct for clang such that their alignment parser can cope
  hack, work around clang __attribute__((packed)) bugs in m30.h and m62.h