Merge autoconf / automake update changes from GCC.

Top level:
	Merge from GCC:
	PR bootstrap/82856
	* multilib.am: New file.  From automake.

config:
	Merge from GCC:
	PR bootstrap/82856
	* math.m4, tls.m4: Use AC_LANG_SOURCE.

zlib:
	Merge from GCC.
	PR bootstrap/82856
	* Makefile.am: Include multilib.am.
	* Makefile.in: Regenerate.

config/math.m4

@@ -25,7 +25,7 @@ AC_DEFUN([GCC_CHECK_MATH_FUNC],
   AC_REQUIRE([GCC_CHECK_LIBM])
   AC_REQUIRE([GCC_CHECK_MATH_HEADERS])
   AC_CACHE_CHECK([for $1], [gcc_cv_math_func_$1],
-		 [AC_LINK_IFELSE([
+		 [AC_LINK_IFELSE([AC_LANG_SOURCE([
 #ifdef HAVE_COMPLEX_H
 #include <complex.h>
 #endif
@@ -40,7 +40,7 @@ main ()
 {
   return 0;
 }
-],
+])],
 [gcc_cv_math_func_$1=yes],
 [gcc_cv_math_func_$1=no])])
   if test $gcc_cv_math_func_$1 = yes; then

config/tls.m4

@@ -4,14 +4,14 @@ AC_DEFUN([GCC_CHECK_TLS], [
   GCC_ENABLE(tls, yes, [], [Use thread-local storage])
   AC_CACHE_CHECK([whether the target supports thread-local storage],
 		 gcc_cv_have_tls, [
-    AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
+    AC_RUN_IFELSE([AC_LANG_SOURCE([__thread int a; int b; int main() { return a = b; }])],
       [dnl If the test case passed with dynamic linking, try again with
        dnl static linking, but only if static linking is supported (not
        dnl on Solaris 10).  This fails with some older Red Hat releases.
       chktls_save_LDFLAGS="$LDFLAGS"
       LDFLAGS="-static $LDFLAGS"
-      AC_LINK_IFELSE([int main() { return 0; }],
-	[AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
+      AC_LINK_IFELSE([AC_LANG_SOURCE([int main() { return 0; }])],
+	[AC_RUN_IFELSE([AC_LANG_SOURCE([__thread int a; int b; int main() { return a = b; }])],
 		       [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[])],
 	[gcc_cv_have_tls=yes])
       LDFLAGS="$chktls_save_LDFLAGS"
@@ -71,7 +71,7 @@ AC_DEFUN([GCC_CHECK_TLS], [
       [gcc_cv_have_tls=no],
       [dnl This is the cross-compiling case. Assume libc supports TLS if the
        dnl binutils and the compiler do.
-       AC_LINK_IFELSE([__thread int a; int b; int main() { return a = b; }],
+       AC_LINK_IFELSE([AC_LANG_SOURCE([__thread int a; int b; int main() { return a = b; }])],
 	 [chktls_save_LDFLAGS="$LDFLAGS"
 	  dnl Shared library options may depend on the host; this check
 	  dnl is only known to be needed for GNU/Linux.
@@ -83,8 +83,8 @@ AC_DEFUN([GCC_CHECK_TLS], [
 	  chktls_save_CFLAGS="$CFLAGS"
 	  CFLAGS="-fPIC $CFLAGS"
 	  dnl If -shared works, test if TLS works in a shared library.
-	  AC_LINK_IFELSE([int f() { return 0; }],
-	    [AC_LINK_IFELSE([__thread int a; int b; int f() { return a = b; }],
+	  AC_LINK_IFELSE([AC_LANG_SOURCE([int f() { return 0; }])],
+	    [AC_LINK_IFELSE([AC_LANG_SOURCE([__thread int a; int b; int f() { return a = b; }])],
 	      [gcc_cv_have_tls=yes],
 	      [gcc_cv_have_tls=no])],
 	    [gcc_cv_have_tls=yes])
@@ -102,7 +102,7 @@ AC_DEFUN([GCC_CHECK_CC_TLS], [
   GCC_ENABLE(tls, yes, [], [Use thread-local storage])
   AC_CACHE_CHECK([whether the target assembler supports thread-local storage],
 		 gcc_cv_have_cc_tls, [
-    AC_COMPILE_IFELSE([__thread int a; int b; int main() { return a = b; }],
+    AC_COMPILE_IFELSE([AC_LANG_SOURCE([__thread int a; int b; int main() { return a = b; }])],
       [gcc_cv_have_cc_tls=yes], [gcc_cv_have_cc_tls=no])]
     )])
   if test "$enable_tls $gcc_cv_have_cc_tls" = "yes yes"; then

multilib.am

@@ -0,0 +1,45 @@
+## automake - create Makefile.in from Makefile.am
+
+## Copyright (C) 1994-2017 Free Software Foundation, Inc.
+## This Makefile.in is free software; the Free Software Foundation
+## gives unlimited permission to copy and/or distribute it,
+## with or without modifications, as long as this notice is preserved.
+
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+
+MULTISRCTOP =
+MULTIBUILDTOP =
+MULTIDIRS =
+MULTISUBDIR =
+MULTIDO = true
+MULTICLEAN = true
+
+# GNU Make needs to see an explicit $(MAKE) variable in the command it
+# runs to enable its job server during parallel builds.  Hence the
+# comments below.
+all-multi:
+	$(MULTIDO) $(AM_MAKEFLAGS) DO=all multi-do # $(MAKE)
+install-multi:
+	$(MULTIDO) $(AM_MAKEFLAGS) DO=install multi-do # $(MAKE)
+mostlyclean-multi:
+	$(MULTICLEAN) $(AM_MAKEFLAGS) DO=mostlyclean multi-clean # $(MAKE)
+clean-multi:
+	$(MULTICLEAN) $(AM_MAKEFLAGS) DO=clean multi-clean # $(MAKE)
+distclean-multi:
+	$(MULTICLEAN) $(AM_MAKEFLAGS) DO=distclean multi-clean # $(MAKE)
+maintainer-clean-multi:
+	$(MULTICLEAN) $(AM_MAKEFLAGS) DO=maintainer-clean multi-clean # $(MAKE)
+
+.MAKE .PHONY: all-multi clean-multi distclean-multi install-am \
+	      install-multi maintainer-clean-multi mostlyclean-multi
+
+install-exec-local: install-multi
+
+all-local: all-multi
+mostlyclean-local: mostlyclean-multi
+clean-local: clean-multi
+distclean-local: distclean-multi
+maintainer-clean-local: maintainer-clean-multi