[PATCH 0/6] v3 of header-check updating patch

I believe I have made all of the changes requested by Eric Blake.
Exposing _AC_INCLUDES_DEFAULT_REQUIREMENTS (now named
AC_CHECK_INCLUDES_DEFAULT) is a separate patch because there was some
uncertainty about whether it was desirable.  Also, I moved the
explanation of C90 headers being generally available to the "Default
Includes" section of the manual, instead of burying them under
AC_HEADER_STDC.  (I'd *like* to revise the manual thoroughly wrt
current portability concerns but I doubt I'll have time in the near
future.)

I've also added a sixth patch that goes through the existing "specific
X" checks and switches them to AC_CHECK_{DECLS,FUNCS,HEADERS}_ONCE
where possible; I think this makes a good deal more sense now that
AC_INCLUDES_DEFAULT uses AC_CHECK_HEADERS_ONCE.  That said, I had an
idea in the shower this morning for eliminating the difference between
the _ONCE macros and the regular macros -- if we did that, we'd just
have to undo this patch -- but I can't be sure the idea will work or
how long it will take me to get to it, so let's not hold this up for
that.


zw

Zack Weinberg (6):
  tests/local.at (AT_CHECK_M4): Support 'stderr' as fourth argument.
  AC_CHECK_HEADER/AC_CHECK_HEADERS: complete transition to compile
    tests.
  Modernize AC_INCLUDES_DEFAULT and friends.
  Use AC_CHECK_HEADERS_ONCE for the tests done by AC_INCLUDES_DEFAULT.
  Use AC_CHECK_{DECLS,FUNCS,HEADERS}_ONCE more in specific-check
    macros.
  Expose the checks done by AC_INCLUDES_DEFAULT as a public macro.

 NEWS                      |   34 +++
 doc/autoconf.texi         |  490 +++++++++++++++++++-------------------------
 lib/autoconf/functions.m4 |   79 +++-----
 lib/autoconf/headers.m4   |  335 +++++++++++--------------------
 tests/c.at                |   28 ++-
 tests/local.at            |    5 +-
 tests/semantics.at        |   19 +-
 tests/tools.at            |    6 +-
 8 files changed, 421 insertions(+), 575 deletions(-)