[patch] lib/autoconf/specific.m4: turn AC_ISC_POSIX into a NOP

[Adrian Bunk]

The platform that needed it saw it's last release in 1998,
is completely unsupported since 2006, and it was already
documented that new programs need not use AC_ISC_POSIX.

The main objective of this change is that without it autoupdate
turned AC_ISC_POSIX into AC_SEARCH_LIBS([strerror],[cposix])
in configure.ac, keeping this zombie alive forever.
---
 doc/autoconf.texi        |    5 ++---
 lib/autoconf/specific.m4 |    2 +-
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 2ae8bb9..a4f6666 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -23411,11 +23411,10 @@ See @ref{AC_FUNC_GETMNTENT} and @ref{AC_CHECK_LIB}.
 @defmac AC_ISC_POSIX
 @acindex{ISC_POSIX}
 @ovindex LIBS
-This macro adds @option{-lcposix} to output variable @code{LIBS} if
+This macro added @option{-lcposix} to output variable @code{LIBS} if
 necessary for Posix facilities.  Sun dropped support for the obsolete
 INTERACTIVE Systems Corporation Unix on 2006-07-23.  New programs
-need not use this macro.  It is implemented as
address@hidden([strerror], [cposix])} (@pxref{AC_SEARCH_LIBS}).
+need not use this macro.  Since autoconf 2.69 it does nothing.
 @end defmac
 
 @defmac AC_LANG_C
diff --git a/lib/autoconf/specific.m4 b/lib/autoconf/specific.m4
index 7d6be57..18a6b52 100644
--- a/lib/autoconf/specific.m4
+++ b/lib/autoconf/specific.m4
@@ -443,7 +443,7 @@ AU_DEFUN([AC_MINIX], [AC_USE_SYSTEM_EXTENSIONS])
 
 # AC_ISC_POSIX
 # ------------
-AU_DEFUN([AC_ISC_POSIX], [AC_SEARCH_LIBS([strerror], [cposix])])
+AU_DEFUN([AC_ISC_POSIX], [])
 
 
 # AC_XENIX_DIR
-- 
1.7.9.5