doc: improve AS_CASE, AS_IF doc
commit3cdc910d229d33e5a98e66b64ee1506a0c2e262c
authorPaul Eggert <eggert@cs.ucla.edu>
Mon, 12 Oct 2020 06:53:41 +0000 (11 23:53 -0700)
committerPaul Eggert <eggert@cs.ucla.edu>
Mon, 12 Oct 2020 06:56:26 +0000 (11 23:56 -0700)
tree17ad4bc40f9c13c53fea5dcf08492326c4b61055
parentd85fc04ed3961f4195b632cd81b89a51216dbea7
doc: improve AS_CASE, AS_IF doc

See the thread containing:
https://lists.gnu.org/r/bug-gnulib/2020-10/msg00033.html
* doc/autoconf.texi: Distinguish between Solaris 10 and later.
(Balancing Parentheses): Mention the Posix syntax for ‘case’,
typically a better solution nowadays.
(AS_CASE, AS_IF): Mention AC_REQUIRE, portability, parens.
(Prerequisite Macros): Tighten up example and make it less dated.
Say that AS_CASE and AS_IF are not needed outside macros.
* NEWS: Don’t mention AS_FOR.  It’s not documented, and for
good reason since it is so ... quirky.
NEWS
doc/autoconf.texi