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

@@ -18,7 +18,7 @@ dnl Process this file with autoconf to produce a configure script.
 
 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

@@ -20,7 +20,7 @@ dnl Process this file with autoconf to produce a configure script.
 
 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

@@ -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

@@ -205,7 +205,7 @@ dnl AM_PROG_LIBTOOL
 
 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