Update from Gnulib

This incorporates:
2018-07-01 getloadavg: don't redefine WINDOWS32
2018-07-01 manywarnings: omit -Wswitch-default
* build-aux/config.sub, lib/getloadavg.c, m4/manywarnings.m4:
Copy from Gnulib.

build-aux/config.sub

@@ -2,7 +2,7 @@
 # Configuration validation subroutine script.
 #   Copyright 1992-2018 Free Software Foundation, Inc.
 
-timestamp='2018-05-24'
+timestamp='2018-07-02'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -1125,6 +1125,12 @@ case $basic_machine in
 	ps2)
 		basic_machine=i386-ibm
 		;;
+	riscv)
+		basic_machine=riscv32-unknown
+		;;
+	riscv-*)
+		basic_machine=`echo "$basic_machine" | sed 's/^riscv/riscv32/'`
+		;;
 	rm[46]00)
 		basic_machine=mips-siemens
 		;;

lib/getloadavg.c

@@ -97,7 +97,7 @@
 
 # include "intprops.h"
 
-# if defined _WIN32 && ! defined __CYGWIN__
+# if defined _WIN32 && ! defined __CYGWIN__ && ! defined WINDOWS32
 #  define WINDOWS32
 # endif
 

m4/manywarnings.m4

@@ -1,4 +1,4 @@
-# manywarnings.m4 serial 15
+# manywarnings.m4 serial 16
 dnl Copyright (C) 2008-2018 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -239,7 +239,6 @@ m4_defun([gl_MANYWARN_ALL_GCC(C)],
     -Wsuggest-final-types \
     -Wswitch \
     -Wswitch-bool \
-    -Wswitch-default \
     -Wswitch-unreachable \
     -Wsync-nand \
     -Wsystem-headers \