autoupdate: replace obsolete macros AC_CONFIG_HEADER

- AC_CONFIG_HEADER by AC_CONFIG_HEADERS
  https://www.gnu.org/software/automake/manual/1.12.2/html_node/Obsolete-Macros.html#index-AM_005fCONFIG_005fHEADER

gdbsupport/configure.ac

diff --git a/gdbsupport/configure.ac b/gdbsupport/configure.ac
index 80e24ea..d0187f8 100644
--- a/gdbsupport/configure.ac
+++ b/gdbsupport/configure.ac
@@ -18,7 +18,7 @@
 
 AC_INIT([gdbsupport], 1.0)
 AC_CONFIG_SRCDIR(common-defs.h)
-AC_CONFIG_HEADER(config.h:config.in)
+AC_CONFIG_HEADERS([config.h:config.in])
 
 # Set build, build_cpu, build_vendor and build_os.
 AC_CANONICAL_BUILD

gnulib/configure.ac

diff --git a/gnulib/configure.ac b/gnulib/configure.ac
index 66a3591..8ee8689 100644
--- a/gnulib/configure.ac
+++ b/gnulib/configure.ac
@@ -20,7 +20,7 @@
 
 AC_INIT([libgnu], [UNUSED-VERSION])
 AC_CONFIG_SRCDIR([import/memmem.c])
-AC_CONFIG_HEADER(config.h:config.in)
+AC_CONFIG_HEADERS([config.h:config.in])
 AC_CONFIG_MACRO_DIRS([import/m4])
 AC_CONFIG_MACRO_DIRS([../config])
 AM_MAINTAINER_MODE

libbacktrace/configure.ac

diff --git a/libbacktrace/configure.ac b/libbacktrace/configure.ac
index c5d84f7..6aa3ceb 100644
--- a/libbacktrace/configure.ac
+++ b/libbacktrace/configure.ac
@@ -31,7 +31,7 @@
 
 AC_INIT(package-unused, version-unused,, libbacktrace)
 AC_CONFIG_SRCDIR(backtrace.h)
-AC_CONFIG_HEADER(config.h)
+AC_CONFIG_HEADERS([config.h])
 
 if test -n "${with_target_subdir}"; then
   AM_ENABLE_MULTILIB(, ..)

libiberty/configure.ac

diff --git a/libiberty/configure.ac b/libiberty/configure.ac
index 4f76b62..c27e08e 100644
--- a/libiberty/configure.ac
+++ b/libiberty/configure.ac
@@ -205,7 +205,7 @@
 
 dnl When we start using automake:
 dnl AM_CONFIG_HEADER(config.h:config.in)
-AC_CONFIG_HEADER(config.h:config.in)
+AC_CONFIG_HEADERS([config.h:config.in])
 
 dnl When we start using automake:
 dnl AM_MAINTAINER_MODE