Merge from Gnulib

This incorporates:
2017-10-29 timespec: prefer ‘assume’ to ‘assure’
2017-10-27 timespec.h: use "assure" to avoid a spurious warning
2017-10-09 getopt-posix: Fix build failure if ac_cv_header_getopt_h=no
* build-aux/config.guess, build-aux/config.sub:
* lib/timespec.h, lib/unistd.in.h:
Copy from Gnulib.

build-aux/config.guess

@@ -2,7 +2,7 @@
 # Attempt to guess a canonical system name.
 #   Copyright 1992-2017 Free Software Foundation, Inc.
 
-timestamp='2017-09-26'
+timestamp='2017-11-01'
 
 # 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
@@ -479,13 +479,13 @@ case "${UNAME_MACHINE}:${UNAME_SYSTEM}:${UNAME_RELEASE}:${UNAME_VERSION}" in
 #endif
 	#if defined (host_mips) && defined (MIPSEB)
 	#if defined (SYSTYPE_SYSV)
-	  printf ("mips-mips-riscos%ssysv\n", argv[1]); exit (0);
+	  printf ("mips-mips-risco0s%ssysv\\n", argv[1]); exit (0);
 	#endif
 	#if defined (SYSTYPE_SVR4)
-	  printf ("mips-mips-riscos%ssvr4\n", argv[1]); exit (0);
+	  printf ("mips-mips-riscos%ssvr4\\n", argv[1]); exit (0);
 	#endif
 	#if defined (SYSTYPE_BSD43) || defined(SYSTYPE_BSD)
-	  printf ("mips-mips-riscos%sbsd\n", argv[1]); exit (0);
+	  printf ("mips-mips-riscos%sbsd\\n", argv[1]); exit (0);
 	#endif
 	#endif
 	  exit (-1);
@@ -608,7 +608,7 @@ EOF
     *:AIX:*:*)
 	echo rs6000-ibm-aix
 	exit ;;
-    ibmrt:4.4BSD:*|romp-ibm:BSD:*)
+    ibmrt:4.4BSD:*|romp-ibm:4.4BSD:*)
 	echo romp-ibm-bsd4.4
 	exit ;;
     ibmrt:*BSD:*|romp-ibm:BSD:*)            # covers RT/PC BSD and
@@ -629,8 +629,8 @@ EOF
     9000/[34678]??:HP-UX:*:*)
 	HPUX_REV=`echo ${UNAME_RELEASE}|sed -e 's/[^.]*.[0B]*//'`
 	case "${UNAME_MACHINE}" in
-	    9000/31? )            HP_ARCH=m68000 ;;
-	    9000/[34]?? )         HP_ARCH=m68k ;;
+	    9000/31?)            HP_ARCH=m68000 ;;
+	    9000/[34]??)         HP_ARCH=m68k ;;
 	    9000/[678][0-9][0-9])
 		if [ -x /usr/bin/getconf ]; then
 		    sc_cpu_version=`/usr/bin/getconf SC_CPU_VERSION 2>/dev/null`
@@ -743,7 +743,7 @@ EOF
 		{ echo "$SYSTEM_NAME"; exit; }
 	echo unknown-hitachi-hiuxwe2
 	exit ;;
-    9000/7??:4.3bsd:*:* | 9000/8?[79]:4.3bsd:*:* )
+    9000/7??:4.3bsd:*:* | 9000/8?[79]:4.3bsd:*:*)
 	echo hppa1.1-hp-bsd
 	exit ;;
     9000/8??:4.3bsd:*:*)
@@ -752,7 +752,7 @@ EOF
     *9??*:MPE/iX:*:* | *3000*:MPE/iX:*:*)
 	echo hppa1.0-hp-mpeix
 	exit ;;
-    hp7??:OSF1:*:* | hp8?[79]:OSF1:*:* )
+    hp7??:OSF1:*:* | hp8?[79]:OSF1:*:*)
 	echo hppa1.1-hp-osf
 	exit ;;
     hp8??:OSF1:*:*)
@@ -1072,7 +1072,7 @@ EOF
     i*86:*DOS:*:*)
 	echo ${UNAME_MACHINE}-pc-msdosdjgpp
 	exit ;;
-    i*86:*:4.*:* | i*86:SYSTEM_V:4.*:*)
+    i*86:*:4.*:*)
 	UNAME_REL=`echo ${UNAME_RELEASE} | sed 's/\/MP$//'`
 	if grep Novell /usr/include/link.h >/dev/null 2>/dev/null; then
 		echo ${UNAME_MACHINE}-univel-sysv${UNAME_REL}

build-aux/config.sub

@@ -2,7 +2,7 @@
 # Configuration validation subroutine script.
 #   Copyright 1992-2017 Free Software Foundation, Inc.
 
-timestamp='2017-09-26'
+timestamp='2017-11-01'
 
 # 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
@@ -640,7 +640,7 @@ case $basic_machine in
 		basic_machine=rs6000-bull
 		os=-bosx
 		;;
-	dpx2* | dpx2*-bull)
+	dpx2*)
 		basic_machine=m68k-bull
 		os=-sysv3
 		;;
@@ -902,7 +902,7 @@ case $basic_machine in
 		basic_machine=v70-nec
 		os=-sysv
 		;;
-	next | m*-next )
+	next | m*-next)
 		basic_machine=m68k-next
 		case $os in
 		    -nextstep* )
@@ -1492,7 +1492,7 @@ case $os in
 	-nova*)
 		os=-rtmk-nova
 		;;
-	-ns2 )
+	-ns2)
 		os=-nextstep2
 		;;
 	-nsk*)
@@ -1694,7 +1694,7 @@ case $basic_machine in
 	m88k-omron*)
 		os=-luna
 		;;
-	*-next )
+	*-next)
 		os=-nextstep
 		;;
 	*-sequent)

lib/timespec.h

@@ -33,6 +33,8 @@ _GL_INLINE_HEADER_BEGIN
 extern "C" {
 #endif
 
+#include "verify.h"
+
 /* Resolution of timespec timestamps (in units per second), and log
    base 10 of the resolution.  */
 
@@ -67,23 +69,29 @@ make_timespec (time_t s, long int ns)
    any platform of interest to the GNU project, since all such
    platforms have 32-bit int or wider.
 
-   Replacing "(int) (a.tv_nsec - b.tv_nsec)" with something like
+   Replacing "a.tv_nsec - b.tv_nsec" with something like
    "a.tv_nsec < b.tv_nsec ? -1 : a.tv_nsec > b.tv_nsec" would cause
    this function to work in some cases where the above assumption is
    violated, but not in all cases (e.g., a.tv_sec==1, a.tv_nsec==-2,
    b.tv_sec==0, b.tv_nsec==999999999) and is arguably not worth the
    extra instructions.  Using a subtraction has the advantage of
    detecting some invalid cases on platforms that detect integer
-   overflow.
-
-   The (int) cast avoids a gcc -Wconversion warning.  */
+   overflow.  */
 
 _GL_TIMESPEC_INLINE int _GL_ATTRIBUTE_PURE
 timespec_cmp (struct timespec a, struct timespec b)
 {
-  return (a.tv_sec < b.tv_sec ? -1
-          : a.tv_sec > b.tv_sec ? 1
-          : (int) (a.tv_nsec - b.tv_nsec));
+  if (a.tv_sec < b.tv_sec)
+    return -1;
+  if (a.tv_sec > b.tv_sec)
+    return 1;
+
+  /* Pacify gcc -Wstrict-overflow (bleeding-edge circa 2017-10-02).  See:
+     http://lists.gnu.org/archive/html/bug-gnulib/2017-10/msg00006.html  */
+  assume (-1 <= a.tv_nsec && a.tv_nsec <= 2 * TIMESPEC_RESOLUTION);
+  assume (-1 <= b.tv_nsec && b.tv_nsec <= 2 * TIMESPEC_RESOLUTION);
+
+  return a.tv_nsec - b.tv_nsec;
 }
 
 /* Return -1, 0, 1, depending on the sign of A.  A.tv_nsec must be

lib/unistd.in.h

@@ -134,9 +134,8 @@
 /* The definition of _GL_WARN_ON_USE is copied here.  */
 
 
-/* Get getopt(), optarg, optind, opterr, optopt.
-   But avoid namespace pollution on glibc systems.  */
-#if @GNULIB_UNISTD_H_GETOPT@ && !defined __GLIBC__ && !defined _GL_SYSTEM_GETOPT
+/* Get getopt(), optarg, optind, opterr, optopt.  */
+#if @GNULIB_UNISTD_H_GETOPT@ && !defined _GL_SYSTEM_GETOPT
 # include <getopt-cdefs.h>
 # include <getopt-pfx-core.h>
 #endif