[PATCH 0/7] Update the compat/regex engine from upstream

See the first patch for motivation & why.

The only reason this has a cover letter is to explain the !fixup commits. IIRC the mailing list has a 100K limit, which this series would violate, so I split up the second commit.

Consider all these !fixup commits to have by Signed-off-by, easier to say that here than to modify them all.

Ævar Arnfjörð Bjarmason (7):
  compat/regex: add a README with a maintenance guide
  compat/regex: update the gawk regex engine from upstream
  fixup! compat/regex: update the gawk regex engine from upstream
  fixup! compat/regex: update the gawk regex engine from upstream
  fixup! compat/regex: update the gawk regex engine from upstream
  fixup! compat/regex: update the gawk regex engine from upstream
  fixup! compat/regex: update the gawk regex engine from upstream

 Makefile                                           |   8 +-
 compat/regex/README                                |  21 +
 compat/regex/intprops.h                            | 448 +++++++++++++++++++++
 .../0001-Add-notice-at-top-of-copied-files.patch   | 120 ++++++
 .../0002-Remove-verify.h-use-from-intprops.h.patch |  41 ++
 compat/regex/regcomp.c                             | 356 +++++++++-------
 compat/regex/regex.c                               |  32 +-
 compat/regex/regex.h                               | 120 +++---
 compat/regex/regex_internal.c                      | 118 +++---
 compat/regex/regex_internal.h                      | 118 +++---
 compat/regex/regexec.c                             | 242 +++++------
 compat/regex/verify.h                              | 286 +++++++++++++
 12 files changed, 1487 insertions(+), 423 deletions(-)
 create mode 100644 compat/regex/README
 create mode 100644 compat/regex/intprops.h
 create mode 100644 compat/regex/patches/0001-Add-notice-at-top-of-copied-files.patch
 create mode 100644 compat/regex/patches/0002-Remove-verify.h-use-from-intprops.h.patch
 create mode 100644 compat/regex/verify.h