Add and use AX_POSIX_SHELL autoconf macro, so we can rely on POSIX shell features

aclocal.m4

@@ -289,6 +289,7 @@ AS_VAR_IF([$1], [""], [$5], [$4])dnl
 ])dnl PKG_CHECK_VAR
 
 m4_include([m4/ax_check_openssl.m4])
+m4_include([m4/ax_posix_shell.m4])
 m4_include([m4/ax_pthread.m4])
 m4_include([m4/libtool.m4])
 m4_include([m4/ltoptions.m4])

configure

@@ -11697,6 +11697,44 @@ else
 $as_echo "no, using $LN_S" >&6; }
 fi
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for a POSIX-compatible shell" >&5
+$as_echo_n "checking for a POSIX-compatible shell... " >&6; }
+if ${ac_cv_prog_shell+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_test_shell_script='
+			  test "$(expr 1 + 1)" = "2" &&
+			  test "$(( 1 + 1 ))" = "2"
+			  '
+
+			  for ac_cv_prog_shell in \
+			    "$CONFIG_SHELL" "$SHELL" /bin/sh /bin/bash /bin/ksh /bin/sh5 no; do
+			    case $ac_cv_prog_shell in #(
+  /*) :
+
+				      if "$ac_cv_prog_shell" -c "$ac_test_shell_script" 2>/dev/null; then :
+  ac_cv_path_shell=$SHELL
+fi
+				     ;; #(
+  *) :
+     ;;
+esac
+			  done
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_shell" >&5
+$as_echo "$ac_cv_prog_shell" >&6; }
+	  if test "$ac_cv_prog_shell" = "no"; then :
+  SHELL=/bin/sh
+		 { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using $SHELL, even though it does not conform to POSIX" >&5
+$as_echo "$as_me: WARNING: using $SHELL, even though it does not conform to POSIX" >&2;}
+
+else
+  SHELL="$ac_cv_prog_shell"
+
+fi
+
+
 
 
 

configure.ac

@@ -24,6 +24,7 @@ AC_PROG_MAKE_SET
 AC_PROG_LIBTOOL
 AC_PROG_INSTALL
 AC_PROG_LN_S
+AX_POSIX_SHELL
 
 AC_SUBST(STD_CINCLUDES)
 AC_SUBST(STD_CDEFINES)

m4/ax_posix_shell.m4

@@ -0,0 +1,28 @@
+# AX_POSIX_SHELL
+# -------------
+# Check for a POSIX-compatible shell.
+#
+AC_DEFUN([AX_POSIX_SHELL],
+	 [AC_CACHE_CHECK([for a POSIX-compatible shell], [ac_cv_prog_shell],
+			 [ac_test_shell_script='
+			  test "$(expr 1 + 1)" = "2" &&
+			  test "$(( 1 + 1 ))" = "2"
+			  '
+
+			  for ac_cv_prog_shell in \
+			    "$CONFIG_SHELL" "$SHELL" /bin/sh /bin/bash /bin/ksh /bin/sh5 no; do
+			    AS_CASE([$ac_cv_prog_shell],
+				    [/*],[
+				      AS_IF(["$ac_cv_prog_shell" -c "$ac_test_shell_script" 2>/dev/null],
+					    [ac_cv_path_shell=$SHELL])
+				    ])
+			  done
+			 ])
+	  AS_IF([test "$ac_cv_prog_shell" = "no"],
+		[SHELL=/bin/sh
+		 AC_MSG_WARN([using $SHELL, even though it does not conform to POSIX])
+		],
+		[SHELL="$ac_cv_prog_shell"
+		])
+	  AC_SUBST([SHELL])
+	 ])

util/copyrights

@@ -3762,13 +3762,6 @@
 ./lib/win32/bindevt/bindevt.vcxproj.in		X	2013,2014,2015,2016,2018
 ./lib/win32/bindevt/bindevt.vcxproj.user	X	2013,2018
 ./ltmain.sh					X	1999,2000,2001,2003,2004,2006,2009,2012,2018
-./m4/ax_check_openssl.m4			X	2018
-./m4/ax_pthread.m4				X	2018
-./m4/libtool.m4					X	2012,2018
-./m4/ltoptions.m4				X	2012,2018
-./m4/ltsugar.m4					X	2012,2018
-./m4/ltversion.m4				X	2012,2018
-./m4/lt~obsolete.m4				X	2012,2018
 ./make/includes.in				MAKE	1999,2000,2001,2004,2005,2007,2012,2014,2016,2017,2018
 ./make/mkdep.in					X	1999,2000,2001,2006,2011,2014,2018
 ./make/rules.in					MAKE	1998,1999,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009,2011,2012,2013,2014,2015,2016,2017,2018